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
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index a2a7536..c16eed8 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -404,6 +404,9 @@
           time python -mtools.codegen.gen -s aten/src/ATen -d build/aten/src/ATen
           time python -mtools.pyi.gen_pyi --native-functions-path aten/src/ATen/native/native_functions.yaml --deprecated-functions-path "tools/autograd/deprecated.yaml"
       - name: Run mypy
+        env:
+          MYPY_FORCE_COLOR: 1
+          TERM: xterm-color
         run: |
           set -eux
           STATUS=