Add type hints to timezone.py

src/linkahead/common/timezone.py

@@ -13,7 +13,7 @@ class TimeZone():
         A human-friendly name of the time zone:
     """
 
-    def __init__(self, zone_id, offset, display_name):
+    def __init__(self, zone_id: str, offset: int, display_name: str):
         self.zone_id = zone_id
         self.offset = offset
         self.display_name = display_name