Bump docker/build-push-action from 5 to 6 (#31)

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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/backend.yml

@@ -86,7 +86,7 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Build and push
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: .
           file: "./src/main/docker/Dockerfile.jvm"

.github/workflows/frontend.yml

@@ -74,7 +74,7 @@ jobs:
 
       - name: Test Docker Build
         if: github.event_name == 'pull_request'
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: "./frontend"
           file: "./frontend/docker/Dockerfile"
@@ -83,7 +83,7 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
       - name: Build and push to all platforms
         if: github.event_name != 'pull_request'
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@v6
         with:
           context: "./frontend"
           file: "./frontend/docker/Dockerfile"