GitLab

All macOS CI jobs were failing at `brew`.
The issue was the macOS version `10.13`, which is no longer supported by `brew`.
The macOS version is indirectly controlled by `xcode` version as listed [here](https://circleci.com/docs/2.0/testing-ios/#supported-xcode-versions).

Updating the `xcode` to `"12.0"` as in PyTorch core bump macOS version to `10.15` and it resolves the issue.
`Python 3.9` is still failing but it's packaging issue on upstream, which needs to be resolved separately.