Enable `local_partial_types` for strict typing [mypy] (#86409)

mypy.ini

@@ -7,6 +7,7 @@ python_version = 3.10
 show_error_codes = true
 follow_imports = silent
 ignore_missing_imports = true
+local_partial_types = true
 strict_equality = true
 no_implicit_optional = true
 warn_incomplete_stub = true

script/hassfest/mypy_config.py

@@ -41,6 +41,7 @@ GENERAL_SETTINGS: Final[dict[str, str]] = {
     "follow_imports": "silent",
     # Enable some checks globally.
     "ignore_missing_imports": "true",
+    "local_partial_types": "true",
     "strict_equality": "true",
     "no_implicit_optional": "true",
     "warn_incomplete_stub": "true",