Also added support for access_token_request hook

Author: violuke

requests_oauthlib/oauth2_session.py

@@ -338,6 +338,10 @@ def fetch_token(
             request_kwargs["params"] = dict(urldecode(body))
         else:
             raise ValueError("The method kwarg must be POST or GET.")
+            
+        for hook in self.compliance_hook["access_token_request"]:
+            log.debug("Invoking access_token_request hook %s.", hook)
+            token_url, headers, request_kwargs = hook(token_url, headers, request_kwargs)
 
         r = self.request(
             method=method,