[.github/actions/build-test-container]: Bump the github-actions group

Bumps the github-actions group in /.github/actions/build-test-container with 2 updates: [actions/cache](https://github.com/actions/cache) and [reproducible-containers/buildkit-cache-dance](https://github.com/reproducible-containers/buildkit-cache-dance).


Updates `actions/cache` from 3 to 4
- [Release notes](https://github.com/actions/cache/releases)
- [Changelog](https://github.com/actions/cache/blob/main/RELEASES.md)
- [Commits](actions/cache@v3...v4)

Updates `reproducible-containers/buildkit-cache-dance` from 2.1.2 to 2.1.4
- [Release notes](https://github.com/reproducible-containers/buildkit-cache-dance/releases)
- [Commits](reproducible-containers/buildkit-cache-dance@v2.1.2...v2.1.4)

---
updated-dependencies:
- dependency-name: actions/cache
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
- dependency-name: reproducible-containers/buildkit-cache-dance
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: github-actions
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/actions/build-test-container/action.yaml

@@ -18,12 +18,12 @@ runs:
     - name: Set up Docker Buildx
       uses: docker/setup-buildx-action@v3
     - name: Cache Template Testing Containers
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: container-test-template-cache
         key: ${{ runner.os }}-test-template-cache-${{ hashFiles('containers/test-template/**') }}-${{ inputs.python-version }}
     - name: Inject container-test-template-cache into docker
-      uses: reproducible-containers/[email protected].2
+      uses: reproducible-containers/[email protected].4
       with:
         cache-source: container-test-template-cache
     - name: Build Docker container for cache