Minor fix to RumbleChatActor().quit() method

- Now sets keep_running to False to kill all internal loops

src/rumchat_actor/__init__.py

@@ -387,6 +387,7 @@ def unpin_message(self):
 
     def quit(self):
         """Shut down everything"""
+        self.keep_running = False
         self.browser.quit()
         # TODO how to close an SSEClient?
         # self.ssechat.client.close()