core/vports: Fix virtual attribute

Author: ccrisan

qtoggleserver/core/vports.py

@@ -12,7 +12,6 @@
 
 class VirtualPort(core_ports.Port):
     WRITABLE = True
-    VIRTUAL = True
 
     def __init__(
         self,
@@ -42,6 +41,9 @@ def map_id(self, new_id: str) -> None:
     def is_integer(self) -> bool:
         return bool(self._integer)
 
+    def attr_is_virtual(self) -> bool:
+        return True
+
     async def read_value(self) -> NullablePortValue:
         return self._virtual_value