Bump docker/build-push-action from v1 to v2

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from v1 to v2.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Changelog](https://github.com/docker/build-push-action/blob/85d408708d8c09e8991e7b18899e77d7aee89287/CHANGELOG.md)
- [Commits](docker/build-push-action@v1...85d4087)

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

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Build and push Docker images
-        uses: docker/build-push-action@v1
+        uses: docker/build-push-action@v2
         with:
           username: ${{ secrets.REGISTRY_USER }}
           password: ${{ secrets.REGISTRY_PASSWORD }}