Fix coreml ios workflow (#78356)
Which were broken by https://pypi.org/project/protobuf/4.21.0/ release
Fix by installing pinned version of coremltools with pinned version of protobuf
Pull Request resolved: https://github.com/pytorch/pytorch/pull/78356
Approved by: https://github.com/atalman
(cherry picked from commit a4723d5a5f11f974f9d9ccd83564f3de5de818c5)
