build(deps): bump docker/build-push-action from 2.8.0 to 2.9.0 (#397)

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>
Co-authored-by: M. J. Fromberger <fromberger@interchain.io>

.github/workflows/proto-dockerfile.yml

@@ -56,7 +56,7 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Build and publish image
-        uses: docker/build-push-action@v2.8.0
+        uses: docker/build-push-action@v2.9.0
         with:
           context: ./proto
           file: ./proto/Dockerfile