Fix regression in verification cog

A stray `bot` was removed from the `on_message` listener, causing it to raise an exception rather than generate a `Context` object from incoming verification channel messages.

bot/cogs/verification.py

@@ -95,7 +95,7 @@ async def on_message(self, message: Message) -> None:
                 ping_everyone=constants.Filter.ping_everyone,
             )
 
-        ctx: Context = await self.get_context(message)
+        ctx: Context = await self.bot.get_context(message)
         if ctx.command is not None and ctx.command.name == "accept":
             return