Try to support RTD older Python version with future import

Author: adamtheturtle

src/mock_vws/database.py

@@ -6,7 +6,7 @@
 
 import uuid
 from dataclasses import dataclass, field
-from typing import Set, TypedDict
+from typing import List, Set, TypedDict
 
 from mock_vws._constants import TargetStatuses
 from mock_vws.states import States
@@ -24,7 +24,7 @@ class DatabaseDict(TypedDict):
     client_access_key: str
     client_secret_key: str
     state_name: str
-    targets: list[TargetDict]
+    targets: List[TargetDict]
 
 
 def _random_hex() -> str:

src/mock_vws/target.py

@@ -23,6 +23,8 @@ class TargetDict(TypedDict):
     A dictionary type which represents a target.
     """
 
+    # We cannot use the `X | Y` sytanx for `Union`s and `Optional`s until
+    # https://github.com/sphinx-doc/sphinx/issues/8775 is resolved.
     name: str
     width: float
     image_base64: str