Fix _QThreadWorker.run not releasing references to fulfilled command object before blocking on next queue.get call

Author: kormax

qasync/__init__.py

@@ -152,6 +152,9 @@ def run(self):
             else:
                 self._logger.debug("Future was canceled")
 
+            # Delete references
+            del command, future, callback, args, kwargs
+
         self._logger.debug("Thread #%s stopped", self.__num)
 
     def wait(self):