Add default value for duration

Author: tetienne

pymfy/api/devices/thermostat.py

@@ -85,7 +85,7 @@ def set_target(
         target_mode: TargetMode,
         target_temperature: int,
         duration_type: DurationType,
-        duration: Optional[int] = None,
+        duration: Optional[int] = -1,
     ) -> None:
         parameters = [
             Parameter("target_mode", target_mode.value),