Update docker/setup-buildx-action action to v3.7.1 (#397)

| datasource  | package                    | from   | to     |
| ----------- | -------------------------- | ------ | ------ |
| github-tags | docker/setup-buildx-action | v3.6.1 | v3.7.1 |

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

@@ -69,7 +69,7 @@ jobs:
           sed -i 's|\${NGINX_PLUS_VERSION}/||g' docker/Dockerfile
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db # v3.6.1
+        uses: docker/setup-buildx-action@c47758b77c9736f4b2ef4073d4d51994fabfe349 # v3.7.1
 
       - name: Build Plus Docker Image
         uses: docker/build-push-action@4f58ea79222b3b9dc2c8bbdd6debcef730109a75 # v6.9.0