Bump docker/build-push-action from 6.13.0 to 6.15.0

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 6.13.0 to 6.15.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@ca877d9...471d1dc)

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

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

.github/workflows/docker-testing.yml

@@ -14,7 +14,7 @@ jobs:
       - name: Checkout Repository
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - uses: docker/setup-buildx-action@6524bf65af31da8d45b59e8c27de4bd072b392f5 # v3.8.0
-      - uses: docker/build-push-action@ca877d9245402d1537745e0e356eab47c3520991 # v6.13.0
+      - uses: docker/build-push-action@471d1dc4e07e5cdedd4c2171150001c434f0b7a4 # v6.15.0
         with:
           context: .
           file: "Dockerfile"