satisfactory: annotate local variables for Cookbook

satisfactory/__init__.py

@@ -1,8 +1,10 @@
 import os
 import json
 
+from typing import Dict
+
 class Cookbook(object):
-    __recipes: dict
+    __recipes: Dict[str, Dict]
 
     def __init__(self, root: str):
         self.__recipes = dict()