Makes localtime/localdate accept optional params

Closes #104

Author: sobolevn

django-stubs/utils/timezone.pyi

@@ -44,8 +44,8 @@ class override(ContextDecorator):
     def __enter__(self) -> None: ...
     def __exit__(self, exc_type: object, exc_value: object, traceback: object) -> None: ...
 
-def localtime(value: _AnyTime, timezone: Optional[tzinfo] = None) -> datetime: ...
-def localdate(value: _AnyTime, timezone: Optional[tzinfo] = None) -> date: ...
+def localtime(value: Optional[_AnyTime], timezone: Optional[tzinfo] = None) -> datetime: ...
+def localdate(value: Optional[_AnyTime], timezone: Optional[tzinfo] = None) -> date: ...
 def now() -> datetime: ...
 def is_aware(value: _AnyTime) -> bool: ...
 def is_naive(value: _AnyTime) -> bool: ...