Pin setup-buildx-action version. Fix Docker build (#94734)
This pins setup-buildx-action version.
Our Docker builds where fixed by: https://github.com/pytorch/pytorch/pull/92702 on Jan 25,26
However setup-builder-action update on Jan 27 broke these builds again.
This PR pins version of setup-buildx-action and fixes Docker builds for nightly.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94734
Approved by: https://github.com/jeanschmidt
