fix: import on Python 3.8 (typing.* runtime aliases)

eventforge/observers.py

@@ -721,8 +721,8 @@ def _register_class_subscriber(
 
 # Each entry: (attr_name, ((target_cls, event), ...)) -- the @observe targets
 # placed on the Reporter method.
-ObserveTargets = tuple[tuple[type, str], ...]
-ReporterMethods = tuple[tuple[str, ObserveTargets], ...]
+ObserveTargets = Tuple[Tuple[type, str], ...]
+ReporterMethods = Tuple[Tuple[str, ObserveTargets], ...]
 
 _REPORTER_OBSERVE_METHODS: weakref.WeakKeyDictionary[type, ReporterMethods] = (
     weakref.WeakKeyDictionary()

eventforge/queue.py

@@ -17,8 +17,10 @@
 from __future__ import annotations
 
 import threading
-from collections.abc import Callable
-from typing import Any, Dict, List, Optional, Tuple, Union, overload
+
+# ``Callable`` is subscripted at runtime in the Handler aliases below; the
+# typing alias is required on Python 3.8 (collections.abc generics are 3.9+).
+from typing import Any, Callable, Dict, List, Optional, Tuple, Union, overload
 from uuid import uuid4
 
 from eventforge.observers import BroadcastDispatcher, Dispatcher, Eventful, Observable

eventforge/task.py

@@ -6,8 +6,10 @@
 import logging
 import threading
 import time
-from collections.abc import Callable
-from typing import Any, Dict, List, Optional, Protocol, Tuple, cast
+
+# ``Callable`` is subscripted at runtime in the ContextHandler alias below; the
+# typing alias is required on Python 3.8 (collections.abc generics are 3.9+).
+from typing import Any, Callable, Dict, List, Optional, Protocol, Tuple, cast
 from uuid import uuid4
 
 from eventforge.executor import ExecutionMode, Executor