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]>

Author: dependabot[bot]

.github/workflows/django.yml

@@ -4,7 +4,7 @@ jobs:
   docker_build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Build docker
         run: docker compose build
       - name: Run ruff
@@ -28,7 +28,7 @@ jobs:
         # needed because the postgres container does not provide a healthcheck
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
         with:
           python-version: 3.10.8
@@ -59,7 +59,7 @@ jobs:
     # The project is currently hosted on render.com
     if: false
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: "0"
       - name: Deploy to Heroku

.github/workflows/rebase_dependencies.yml

@@ -8,7 +8,7 @@ jobs:
     name: Rebase `dependencies` with `master`
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0 # otherwise, you will fail to push refs to dest repo
           ref: dependencies