ci(deps): bump docker/setup-buildx-action from 1 to 2

Bumps [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) from 1 to 2.
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](https://github.com/docker/setup-buildx-action/compare/v1...v2)

---
updated-dependencies:
- dependency-name: docker/setup-buildx-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/release-rc.yml

@@ -41,7 +41,7 @@ jobs:
         password: ${{ secrets.DOCKER_REGISTRY_ON_GITHUB_PASSWORD }}
 
     - name: Set up Docker Buildx
-      uses: docker/setup-buildx-action@v1
+      uses: docker/setup-buildx-action@v2
 
     - name: Build and push
       uses: docker/build-push-action@v2

.github/workflows/release-slackbot-proxy.yml

@@ -55,7 +55,7 @@ jobs:
         gcloud auth configure-docker --quiet
 
     - name: Set up Docker Buildx
-      uses: docker/setup-buildx-action@v1
+      uses: docker/setup-buildx-action@v2
 
     - name: Build and push
       uses: docker/build-push-action@v2