Add should_strip_auth to requests SessionRedirectMixin (#5439)

stubs/requests/requests/sessions.pyi

@@ -41,6 +41,7 @@ class SessionRedirectMixin:
     def resolve_redirects(self, resp, req, stream=..., timeout=..., verify=..., cert=..., proxies=...): ...
     def rebuild_auth(self, prepared_request, response): ...
     def rebuild_proxies(self, prepared_request, proxies): ...
+    def should_strip_auth(self, old_url, new_url): ...
 
 _Data = Union[None, Text, bytes, Mapping[str, Any], Mapping[Text, Any], Iterable[Tuple[Text, Optional[Text]]], IO]