Added annotation for fetch_request_token of OAuth1Client class (#14711)

Author: Spider84pr

stubs/Authlib/authlib/oauth1/client.pyi

@@ -1,4 +1,5 @@
 from _typeshed import Incomplete
+from typing import Any
 
 from authlib.oauth1 import ClientAuth
 
@@ -31,7 +32,7 @@ class OAuth1Client:
     @token.setter
     def token(self, token) -> None: ...
     def create_authorization_url(self, url, request_token=None, **kwargs): ...
-    def fetch_request_token(self, url, **kwargs): ...
+    def fetch_request_token(self, url: str, **kwargs) -> dict[str, Any]: ...
     def fetch_access_token(self, url, verifier=None, **kwargs): ...
     def parse_authorization_response(self, url): ...
     def parse_response_token(self, status_code, text): ...