ci: bump docker/setup-buildx-action from 2 to 3

Bumps [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) from 2 to 3.
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](docker/setup-buildx-action@v2...v3)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/docker.yml

@@ -62,7 +62,7 @@ jobs:
           echo "::set-output name=created::$(date -u +'%Y-%m-%dT%H:%M:%SZ')"
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v2
+        uses: docker/setup-buildx-action@v3
 
       - name: "Rebuild oasisprotocol/oasis-rosetta-gateway:${{ steps.branch_tag.outputs.tag }}"
         uses: docker/[email protected]