build(deps): bump docker/build-push-action from v1 to v2.1.0 (#764)

Bumps [docker/build-push-action](https://github.com/docker/build-push-action) from v1 to v2.1.0.
- [Release notes](https://github.com/docker/build-push-action/releases)
- [Commits](docker/build-push-action@v1...6efc2b0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Kyle Conroy <kyle@conroy.org>

Author: dependabot[bot]

.github/workflows/docker.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: docker/build-push-action@v1
+    - uses: docker/build-push-action@v2.1.0
       with:
         username: kjconroy
         password: ${{ secrets.DOCKER_PASSWORD }}