App.NoopCompleter: Fix argcomplete 3.7 type errors

argcomplete 3.7 declares BaseCompleter.__call__() with an Iterable return,
and mypy rejects the None-returning override in NoopCompleter. Return an
empty list instead.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/App.py

@@ -407,8 +407,9 @@ class App:  # export
 
                 @override
                 def __call__(  # pyright: ignore[reportGeneralTypeIssues]
-                        self, *args: Any, **kwargs: Any) -> None:
-                    return None
+                        self, *args: Any, **kwargs: Any,
+                ) -> list[str]:
+                    return []
 
             import argcomplete  # type: ignore[import-not-found, unused-ignore]