Bump docker/build-push-action from 5 to 6

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 5 to 6.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v5...v6)

---
updated-dependencies:
- dependency-name: docker/build-push-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/deployment-tests.yml

@@ -23,7 +23,7 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Build and push
         id: docker_build
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           push: true
           file: containers/cobald-tardis-deployment-test-env/Dockerfile.${{ matrix.os_container }}

.github/workflows/docker-builds.yml

@@ -59,7 +59,7 @@ jobs:
             password: ${{ secrets.DOCKERHUB_TOKEN }}
         - name: Build
           id: docker_build
-          uses: docker/build-push-action@v5
+          uses: docker/build-push-action@v6
           with:
             context: containers/${{ matrix.containers }}
             push: ${{ github.repository == 'MatterMiners/tardis' && github.event_name != 'pull_request' }}