build(deps): Bump docker/setup-buildx-action from v1.1.2 to v1.2.0 (#6391)

Bumps [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) from v1.1.2 to v1.2.0.
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](https://github.com/docker/setup-buildx-action/compare/v1.1.2...012185ccbeb554a7f5f987bea0f1a73519b3cdf5)

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

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

.github/workflows/docker.yml

@@ -40,7 +40,7 @@ jobs:
           platforms: all
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v1.1.2
+        uses: docker/setup-buildx-action@v1.2.0
 
       - name: Login to DockerHub
         if: ${{ github.event_name != 'pull_request' }}

.github/workflows/proto-docker.yml

@@ -34,7 +34,7 @@ jobs:
           echo ::set-output name=tags::${TAGS}
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v1.1.2
+        uses: docker/setup-buildx-action@v1.2.0
 
       - name: Login to DockerHub
         uses: docker/login-action@v1