Bump actions/checkout from 3 to 4

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>

.github/workflows/release.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Install tox
         run: python3 -m pip install --user "tox>=4.0.0"
       - name: Check out src from Git
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0 # needed by setuptools-scm
       - name: Build dists

.github/workflows/tox.yml

@@ -49,7 +49,7 @@ jobs:
       PYTEST_REQPASS: 1
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # needed by setuptools-scm
 
@@ -130,7 +130,7 @@ jobs:
           jobs: ${{ toJSON(needs) }}
 
       - name: Check out src from Git
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Notify repository owners about lint change affecting them
         uses: sourcegraph/codenotify@v0.6.4