filtermail: further optimize check_armored_payload()

Author: missytake

chatmaild/src/chatmaild/filtermail.py

@@ -106,7 +106,7 @@ def check_armored_payload(payload: str, outgoing: bool):
         if outgoing:  # Disallow comments in outgoing messages
             return False
         # Remove comments from incoming messages
-        payload = payload.split("\r\n", maxsplit=1)[1]
+        payload = payload.partition("\r\n")[2]
 
     while payload.startswith("\r\n"):
         payload = payload.removeprefix("\r\n")