Use portable filter to match all files in getFile (#1943)

`*.*` matches files with no extensions on Windows, while it doesn't do so on
macOS.

Reference: https://doc.qt.io/qt-6/qfiledialog.html#setNameFilters

qt/aqt/utils.py

@@ -430,7 +430,7 @@ def getFile(
     title: str,
     # single file returned unless multi=True
     cb: Callable[[str | Sequence[str]], None] | None,
-    filter: str = "*.*",
+    filter: str = "*",
     dir: str | None = None,
     key: str | None = None,
     multi: bool = False,  # controls whether a single or multiple files is returned