Bump actions/checkout from 2 to 2.3.4 (#592)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 2.3.4.
<details>
<summary>Release notes</summary>
<p><em>Sourced from <a href="https://github.com/actions/checkout/releases">actions/checkout's releases</a>.</em></p>
<blockquote>
<h2>v2.3.4</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/379">Add missing <code>await</code>s</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/360">Swap to Environment Files</a></li>
</ul>
<h2>v2.3.3</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/345">Remove Unneeded commit information from build logs</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/326">Add Licensed to verify third party dependencies</a></li>
</ul>
<h2>v2.3.2</h2>
<p><a href="https://github-redirect.dependabot.com/actions/checkout/pull/320">Add Third Party License Information to Dist Files</a></p>
<h2>v2.3.1</h2>
<p><a href="https://github-redirect.dependabot.com/actions/checkout/pull/284">Fix default branch resolution for .wiki and when using SSH</a></p>
<h2>v2.3.0</h2>
<p><a href="https://github-redirect.dependabot.com/actions/checkout/pull/278">Fallback to the default branch</a></p>
<h2>v2.2.0</h2>
<p><a href="https://github-redirect.dependabot.com/actions/checkout/pull/258">Fetch all history for all tags and branches when fetch-depth=0</a></p>
<h2>v2.1.1</h2>
<p>Changes to support GHES (<a href="https://github-redirect.dependabot.com/actions/checkout/pull/236">here</a> and <a href="https://github-redirect.dependabot.com/actions/checkout/pull/248">here</a>)</p>
<h2>v2.1.0</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/191">Group output</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/199">Changes to support GHES alpha release</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/184">Persist core.sshCommand for submodules</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/163">Add support ssh</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/179">Convert submodule SSH URL to HTTPS, when not using SSH</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/157">Add submodule support</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/144">Follow proxy settings</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/141">Fix ref for pr closed event when a pr is merged</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/128">Fix issue checking detached when git less than 2.22</a></li>
</ul>
</blockquote>
</details>
<details>
<summary>Changelog</summary>
<p><em>Sourced from <a href="https://github.com/actions/checkout/blob/main/CHANGELOG.md">actions/checkout's changelog</a>.</em></p>
<blockquote>
<h1>Changelog</h1>
<h2>v2.3.1</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/284">Fix default branch resolution for .wiki and when using SSH</a></li>
</ul>
<h2>v2.3.0</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/278">Fallback to the default branch</a></li>
</ul>
<h2>v2.2.0</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/258">Fetch all history for all tags and branches when fetch-depth=0</a></li>
</ul>
<h2>v2.1.1</h2>
<ul>
<li>Changes to support GHES (<a href="https://github-redirect.dependabot.com/actions/checkout/pull/236">here</a> and <a href="https://github-redirect.dependabot.com/actions/checkout/pull/248">here</a>)</li>
</ul>
<h2>v2.1.0</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/191">Group output</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/199">Changes to support GHES alpha release</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/184">Persist core.sshCommand for submodules</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/163">Add support ssh</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/179">Convert submodule SSH URL to HTTPS, when not using SSH</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/157">Add submodule support</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/144">Follow proxy settings</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/141">Fix ref for pr closed event when a pr is merged</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/128">Fix issue checking detached when git less than 2.22</a></li>
</ul>
<h2>v2.0.0</h2>
<ul>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/108">Do not pass cred on command line</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/107">Add input persist-credentials</a></li>
<li><a href="https://github-redirect.dependabot.com/actions/checkout/pull/104">Fallback to REST API to download repo</a></li>
</ul>
</blockquote>
</details>
<details>
<summary>Commits</summary>
<ul>
<li>See full diff in <a href="https://github.com/actions/checkout/compare/v2...v2.3.4">compare view</a></li>
</ul>
</details>
<br />


[![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility_score?dependency-name=actions/checkout&package-manager=github_actions&previous-version=2&new-version=2.3.4)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores)

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`.

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.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
     timeout-minutes: 5
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
     - name: Setup Python 3.9
       uses: actions/setup-python@v2.2.2
       with:
@@ -80,7 +80,7 @@ jobs:
     timeout-minutes: 15
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
     - name: Setup Python ${{ matrix.pyver }}
       uses: actions/setup-python@v2.2.2
       with:
@@ -133,7 +133,7 @@ jobs:
     needs: pre-deploy
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
     - name: Setup Python 3.8
       uses: actions/setup-python@v2.2.2
       with:
@@ -161,7 +161,7 @@ jobs:
     needs: pre-deploy
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
     - name: Set up QEMU
       id: qemu
       uses: docker/setup-qemu-action@v1
@@ -200,7 +200,7 @@ jobs:
     needs: pre-deploy
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v2.3.4
     - name: Setup Python 3.8
       uses: actions/setup-python@v2.2.2
       with: