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/docker-testing.yml

@@ -11,7 +11,7 @@ jobs:
     name: Build Docker image
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: docker/setup-buildx-action@v2
       - uses: docker/build-push-action@v4
         with:

.github/workflows/main.yml

@@ -18,7 +18,7 @@ jobs:
         uses: styfle/[email protected]
         with:
             access_token: ${{ github.token }}
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: actions/setup-python@v4
         with:
           python-version: "3.11"
@@ -44,7 +44,7 @@ jobs:
           - os: macos-latest
             python-version: "3.10"
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Setup Conda (Micromamba) with Python${{ matrix.python-version }}
         uses: mamba-org/setup-micromamba@v1
         with: