Do not update max_packet_size if not explicitly specified

rcon/client.py

@@ -9,6 +9,8 @@ __all__ = ['BaseClient']
 class BaseClient:
     """A common RCON client."""
 
+    _max_pkg_size: int | None = None
+
     def __init__(
             self, host: str, port: int, *,
             timeout: float | None = None,
@@ -30,6 +32,7 @@ class BaseClient:
         if socket_type is not None:
             cls._socket_type = socket_type
 
+        if max_pkg_size is not None:
             cls._max_pkg_size = max_pkg_size
 
     def __enter__(self):