Update docker/build-push-action action to v7

| datasource  | package                  | from | to |
| ----------- | ------------------------ | ---- | -- |
| github-tags | docker/build-push-action | v6   | v7 |


Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/build-docker.yml

@@ -62,7 +62,7 @@ jobs:
           password: ${{ secrets.DOCKER_PASSWORD }}
         if: ${{ steps.update.outputs.needs-updating == 'true' || inputs.force == 'true' }}
       - name: Push to Dockerhub for nginx-hello
-        uses: docker/build-push-action@10e90e3645eae34f1e60eeb005ba3a3d33f178e8 # v6
+        uses: docker/build-push-action@bcafcacb16a39f128d818304e6c9c0c18556b85f # v7
         with:
           context: ${{ matrix.context }}
           file: ${{ matrix.file }}