Fix missing line

Author: javizqh

manager/manager/launcher/launcher_gzsim.py

@@ -59,6 +59,7 @@ class LauncherGzsim(ILauncher):
     height: int
     width: int
     running: bool = False
+    acceptsMsgs: bool = False
     threads: List[Any] = []
     gz_vnc: Any = Vnc_server()