Enable Ruff N (pep8-naming) on non-stubs (#13327)

pyproject.toml

@@ -41,6 +41,7 @@ select = [
     "B", # flake8-bugbear
     "FA", # flake8-future-annotations
     "I", # isort
+    "N", # pep8-naming
     "PGH", # pygrep-hooks
     "RUF", # Ruff-specific and unused-noqa
     "UP", # pyupgrade
@@ -118,6 +119,9 @@ ignore = [
     # See https://github.com/python/typeshed/pull/13108
     "RUF022",
     "RUF023",
+    # Most pep8-naming rules don't apply for third-party stubs like typeshed.
+    # N811 to N814 could apply, but we often use them to disambiguate a name whilst making it look like a more common one
+    "N8",
     # Rules that are out of the control of stub authors:
     "F403", # `from . import *` used; unable to detect undefined names
     # Stubs can sometimes re-export entire modules.