Fixed http invalid

[edoardoscarpaci]

apispec.exceptions.APISpecError: One or more HTTP methods are invalid: unlock, report, copy, move, trace, checkout, update, lock, websocket, mkcol, checkin, connect, propfind, proppatch, uncheckin, version-control
Fixed by chaning method_handler.dict.get("module") to "falcon.responders": method_handler.module == "falcon.responders":