Bump docker/setup-buildx-action (#71)

Bumps [docker/setup-buildx-action](https://github.com/docker/setup-buildx-action) from 79abd3f86f79a9d68a23c75a09a9a85889262adf to edfb0fe6204400c56fbfd3feba3fe9ad1adfa345.
- [Release notes](https://github.com/docker/setup-buildx-action/releases)
- [Commits](docker/setup-buildx-action@79abd3f...edfb0fe)

---
updated-dependencies:
- dependency-name: docker/setup-buildx-action
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/sign-container.yaml

@@ -36,7 +36,7 @@ jobs:
 
       # Workaround: https://github.com/docker/build-push-action/issues/461
       - name: Setup Docker buildx
-        uses: docker/setup-buildx-action@79abd3f86f79a9d68a23c75a09a9a85889262adf
+        uses: docker/setup-buildx-action@edfb0fe6204400c56fbfd3feba3fe9ad1adfa345
 
       # Login against a Docker registry except on PR
       # https://github.com/docker/login-action