feat: small speed up to processing bluez passive data

This is a ~5% speed up

src/dbus_fast/message_bus.pxd

@@ -11,12 +11,12 @@ cdef object MessageFlag
 cdef object MESSAGE_TYPE_CALL
 cdef object MESSAGE_TYPE_SIGNAL
 cdef object NO_REPLY_EXPECTED_VALUE
+cdef object SWALLOW_UNEXPECTED_REPLY
 cdef object assert_object_path_valid
 cdef object assert_bus_name_valid
 
 cdef _expects_reply(Message msg)
 
-cpdef _swallow_unexpected_reply(Message msg)
 
 cdef class SendReply:
 

src/dbus_fast/message_bus.py

@@ -41,6 +41,9 @@ def _swallow_unexpected_reply(msg: _Message) -> None:
     """Swallow a reply if it's not expected."""
 
 
+SWALLOW_UNEXPECTED_REPLY = _swallow_unexpected_reply
+
+
 class SendReply:
     """A context manager to send a reply to a message."""
 
@@ -860,7 +863,7 @@ def _process_message(self, msg: _Message) -> None:
             if not handled:
                 handler = self._find_message_handler(msg)
                 if not _expects_reply(msg):
-                    handler(msg, _swallow_unexpected_reply)
+                    handler(msg, SWALLOW_UNEXPECTED_REPLY)
                     return
 
                 send_reply = SendReply(self, msg)