Fix lint which broke in #18374 (#18385)

#18374 did not pass linting
but was merged

Author: sandhose

changelog.d/18385.misc

@@ -0,0 +1 @@
+Don't validate the `at_hash` (access token hash) field in OIDC ID Tokens if we don't end up actually using the OIDC Access Token.

synapse/handlers/oidc.py

@@ -599,7 +599,7 @@ def _uses_access_token(self) -> bool:
         # from the userinfo endpoint. Therefore we only have a single criteria
         # to check right now but this may change in the future and this function
         # should be updated if more usages are introduced.
-        # 
+        #
         # For example, if we start to use the access_token given to us by the
         # IdP for more things, such as accessing Resource Server APIs.
         return self._uses_userinfo