Bump docker/build-push-action from 2.8.0 to 2.9.0 (#3497)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from 2.8.0 to 2.9.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](https://github.com/docker/build-push-action/compare/v2.8.0...v2.9.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

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

.github/workflows/cd.yml

@@ -63,7 +63,7 @@ jobs:
     # Build and push image to Google Artifact Registry
     - name: Build & push
       id: docker_build
-      uses: docker/build-push-action@v2.8.0
+      uses: docker/build-push-action@v2.9.0
       with:
         target: runtime
         context: .

.github/workflows/zcash-params.yml

@@ -53,7 +53,7 @@ jobs:
     # Build and push image to Google Artifact Registry
     - name: Build & push
       id: docker_build
-      uses: docker/build-push-action@v2.8.0
+      uses: docker/build-push-action@v2.9.0
       with:
         target: builder
         context: .