Properly handle unavailable port value writes

Author: ccrisan

qtoggleserver/modbus/ports.py

@@ -103,6 +103,7 @@ async def read_value(self) -> NullablePortValue:
 
         return value
 
+    @core_ports.skip_write_unavailable
     async def write_value(self, value: PortValue) -> None:
         client = self.get_peripheral()