misc: drop typing as T, use builtin generics

Python 3.10 is the minimum, so annotations use `X | None`, `list[X]`
and friends, enforced by ruff's pyupgrade rules. The remaining typing
names are imported directly, with abstract types coming from
collections.abc. first() is now generic over the item and default.

pqcli/ui/curses/event_handler.py

@@ -1,14 +1,15 @@
-import typing as T
+from collections.abc import Callable
+from typing import Any
 
 
 class EventHandler:
     def __init__(self) -> None:
-        self.callbacks: T.List[T.Callable[..., T.Any]] = []
+        self.callbacks: list[Callable[..., Any]] = []
 
-    def __call__(self, *args: T.Any, **kwargs: T.Any) -> None:
+    def __call__(self, *args: Any, **kwargs: Any) -> None:
         for callback in self.callbacks:
             callback(*args, **kwargs)
 
-    def __iadd__(self, callback: T.Callable[..., T.Any]) -> "EventHandler":
+    def __iadd__(self, callback: Callable[..., Any]) -> "EventHandler":
         self.callbacks.append(callback)
         return self