ci: 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/pytest.yml

@@ -32,7 +32,7 @@ jobs:
 
     steps:
       - name: "Checkout repository"
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: "Run container-pre-test.sh"
         run: |

.github/workflows/stylish.yml

@@ -19,7 +19,7 @@ jobs:
             python3-flake8 \
             rpmlint
 
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup flake8 annotations
       uses: rbialon/flake8-annotations@v1