Bump actions/checkout from 2 to 2.3.4 (#2293)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 2.3.4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...v2.3.4)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -34,7 +34,7 @@ jobs:
     steps:
 
     - name: 1. Check out code
-      uses: actions/checkout@v2 # https://github.com/actions/checkout
+      uses: actions/checkout@v2.3.4 # https://github.com/actions/checkout
       with:
         fetch-depth: '0' # https://github.com/shipkit/shipkit-changelog#fetch-depth-on-ci
 
@@ -81,7 +81,7 @@ jobs:
     steps:
 
       - name: Check out code
-        uses: actions/checkout@v2 # https://github.com/actions/checkout
+        uses: actions/checkout@v2.3.4 # https://github.com/actions/checkout
         with:
           fetch-depth: '0' # https://github.com/shipkit/shipkit-changelog#fetch-depth-on-ci