Use default symbol theme if none is provided when loading appliances

gns3server/api/routes/controller/appliances.py

@@ -47,7 +47,7 @@ router = APIRouter()
 @router.get("")
 async def get_appliances(
         update: Optional[bool] = False,
-        symbol_theme: Optional[str] = "Classic"
+        symbol_theme: Optional[str] = None
 ) -> List[schemas.Appliance]:
     """
     Return all appliances known by the controller.
@@ -56,7 +56,7 @@ async def get_appliances(
     controller = Controller.instance()
     if update:
         await controller.appliance_manager.download_appliances()
-    controller.appliance_manager.load_appliances(symbol_theme=symbol_theme)
+    controller.appliance_manager.load_appliances(symbol_theme)
     return [c.asdict() for c in controller.appliance_manager.appliances.values()]