mab update, !short command, last_access fix

- Updated mab to v0.5.0
- Added `!short` command to add named tokens
- Fixed `last_access_at` field not being updated

main.py

@@ -55,7 +55,7 @@ async def main() -> None:
     if not await db.connect():
         util.log_error("Can't connect to the database!")
         return
-    bot.start()
+    await bot.start()
     await web_server.start()
 
     # wait for Ctrl+C