Bump actions/checkout from 3 to 4 (#168)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

Author: dependabot[bot]

.github/workflows/release.yml

@@ -28,7 +28,7 @@ jobs:
         run: python3 -m pip install --user tox
 
       - name: Check out src from Git
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # needed by setuptools-scm
 

.github/workflows/tox.yml

@@ -71,7 +71,7 @@ jobs:
           path: ~/.vagrant.d/boxes
           key: ${{ runner.os }}-vagrant-${{ hashFiles('**/Vagrantfile') }}
 
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # needed by setuptools-scm