Fix Paginator properties mistyped as Callables (#193)

Co-authored-by: Nick Sweeting <git@sweeting.me>

django-stubs/core/paginator.pyi

@@ -32,7 +32,9 @@ class Paginator:
     def validate_number(self, number: Optional[Union[float, str]]) -> int: ...
     def get_page(self, number: Optional[int]) -> Page: ...
     def page(self, number: Union[int, str]) -> Page: ...
+    @property
     def count(self) -> int: ...
+    @property
     def num_pages(self) -> int: ...
     @property
     def page_range(self) -> range: ...