Make TextChannel._get_channel async (#1358)

Author: Qxe5

discord/channel.py

@@ -713,7 +713,7 @@ def _repr_attrs(self) -> Tuple[str, ...]:
     def _update(self, guild: Guild, data: TextChannelPayload) -> None:
         super()._update(guild, data)
 
-    def _get_channel(self) -> "TextChannel":
+    async def _get_channel(self) -> "TextChannel":
         return self
 
     def is_news(self) -> bool: