Run mypy on the lowest supported Python version instead of system Python (#27048)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

.pre-commit-config.yaml

@@ -48,8 +48,8 @@ repos:
     entry: python tools/generate_nightly_torch_test.py
     files: ^requirements/test\.(in|txt)$
   - id: mypy-local
-    name: Run mypy for local Python installation
-    entry: python tools/pre_commit/mypy.py 0 "local"
+    name: Run mypy locally for lowest supported Python version
+    entry: python tools/pre_commit/mypy.py 0 "3.10"
     stages: [pre-commit] # Don't run in CI
     <<: &mypy_common
       language: python