Add log message for comparing controller version with config version. Ref https://github.com/GNS3/gns3-gui/issues/3486

gns3server/controller/__init__.py

@@ -251,6 +251,7 @@ class Controller:
             self._iou_license_settings = controller_settings["iou_license"]
 
         previous_version = controller_settings.get("version")
+        log.info("Comparing controller version {} with config version {}".format(__version__, previous_version))
         if not previous_version or \
                 parse_version(__version__.split("+")[0]) > parse_version(previous_version.split("+")[0]):
             self._appliance_manager.install_builtin_appliances()