Fix removeprefix issue by @Jerrie-Aries ecc92e4#r83768323

Author: fourjr

bot.py

@@ -1000,7 +1000,8 @@ async def get_contexts(self, message, *, cls=commands.Context):
         # This needs to be done before checking for aliases since
         # snippets can have multiple words.
         try:
-            snippet_text = self.snippets[message.content.strip(invoked_prefix)]
+            # Use removeprefix once PY3.9+
+            snippet_text = self.snippets[message.content[len(invoked_prefix) :]]
         except KeyError:
             snippet_text = None