Bump actions/setup-python from 2 to 4

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 2 to 4.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v2...v4)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/release.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
     - name: Switch to using Python 3.8 by default
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v4
       with:
         python-version: 3.8
     - name: Install tox

.github/workflows/tox.yml

@@ -41,15 +41,11 @@ jobs:
           v = '${{ matrix.tox_env }}'.split('-')[0].lstrip('py')
           print('::set-output name=version::{0}.{1}'.format(v[0],v[1:]))
       # Even our lint and other envs need access to tox
-      - name: Install a default Python
-        uses: actions/setup-python@v2
+      - name: Install Python
+        uses: actions/setup-python@v4
         if: ${{ ! contains(matrix.tox_env, 'py') }}
-      # Be sure to install the version of python needed by a specific test, if necessary
-      - name: Set up Python version
-        uses: actions/setup-python@v2
-        if: ${{ contains(matrix.tox_env, 'py') }}
         with:
-          python-version: ${{ steps.py_ver.outputs.version }}
+          python-version: ${{ steps.py_ver.outputs.version || '>=3.8' }}
       - name: Install dependencies
         run: |
           python -m pip install -U pip