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] <[email protected]>

.github/workflows/ci.yml

@@ -5,23 +5,23 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/[email protected]
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: python -m pip install --upgrade black
       - run: black --check .
 
   flake8:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/[email protected]
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: python -m pip install flake8
       - run: flake8
 
   isort:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/[email protected]
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - run: python -m pip install -r requirements/common.pip isort==5.6.4
       - run: isort --diff --check django_tables2 test
 
@@ -42,7 +42,7 @@ jobs:
         uses: actions/[email protected]
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/[email protected]
         with:
           path: ~/.cache/pip
@@ -61,7 +61,7 @@ jobs:
   docs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/[email protected]
         with:
             python-version: "3.11"