Update docker/build-push-action action to v6.18.0 (#511)

| datasource  | package                  | from    | to      |
| ----------- | ------------------------ | ------- | ------- |
| github-tags | docker/build-push-action | v6.16.0 | v6.18.0 |

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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -72,7 +72,7 @@ jobs:
         uses: docker/setup-buildx-action@b5ca514318bd6ebac0fb2aedd5d36ec1b5c232a2 # v3.10.0
 
       - name: Build Plus Docker Image
-        uses: docker/build-push-action@14487ce63c7a62a4a324b0bfb37086795e31c6c1 # v6.16.0
+        uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
         with:
           file: docker/Dockerfile
           tags: nginx-plus