Mod: fix mod enabling/disabling multiple times

I forgot to update the enabled variable, so this would only work the
first time it gets called

src/leek/mod.py

@@ -49,6 +49,7 @@ class Mod:
         with config_toml.open("w") as config_file:
             self.__config["enabled"] = value
             tomlkit.dump(self.__config, config_file)
+            self.__enabled = value
 
     def __init__(self, path: Path) -> None:
         self.__path = path