Force mypy colors in CI (#61391)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61391
Both the [GitHub Actions log viewer](https://github.community/t/ansi-color-output-in-webview/17621) and the HUD PR page log viewer support ANSI color codes so turn those on via this [secret env variable](https://github.com/python/mypy/issues/7771)
Test Plan: Imported from OSS
Reviewed By: walterddr
Differential Revision: D29602686
Pulled By: driazati
fbshipit-source-id: e8f4cd71572cc068927e6719534e64773cb16c7f
