Close arkhamdb session in a more clean way

ahtcg_bot.py

@@ -25,6 +25,10 @@ class ArkhamDBUpdater(commands.Bot):
         self.arkhamdb_client = ArkhamDBClient()
         self.setup_commands()
 
+    async def close(self) -> None:
+        await self.arkhamdb_client.close()
+        await super().close()
+
     def setup_commands(self):
         @self.command(name='monitor')
         async def monitor(ctx: commands.Context):

arkhamdb.py

@@ -17,10 +17,6 @@ class ArkhamDBClient:
         self._session = aiohttp.ClientSession()
         self.origin = arkhamdb_origin
 
-    def __del__(self):
-        loop = asyncio.get_event_loop()
-        loop.run_until_complete(self.close())
-
     async def close(self):
         await self._session.close()