fix typing for URL validator.__call__ (typeddjango#2074)

while it will only be successful for `str`, the first step of the validator is to check the type.  this matches the RegexValidator above

Author: asottile

django-stubs/core/validators.pyi

@@ -42,7 +42,7 @@ class URLValidator(RegexValidator):
     unsafe_chars: frozenset[str]
     max_length: int
     def __init__(self, schemes: Sequence[str] | None = ..., **kwargs: Any) -> None: ...
-    def __call__(self, value: str) -> None: ...
+    def __call__(self, value: Any) -> None: ...
 
 integer_validator: RegexValidator