Fix webconfig import

Fixes 78f71971cb (fix: Python 3.5+ compatibility in webconfig.py
type hints, 2025-11-09).
Fixes #12053

CHANGELOG.rst

@@ -1,6 +1,10 @@
-fish ?.?.? (released ???)
+fish 4.2.1 (released ???)
 =========================
 
+This release fixes the following problems identified in 4.2.0:
+
+- ``fish_config``'s theme selector (the "colors" tab) was broken, which has been fixed (:issue:`12053`).
+
 fish 4.2.0 (released November 10, 2025)
 =======================================
 

share/tools/web_config/webconfig.py

@@ -19,7 +19,7 @@ import subprocess
 import sys
 import tempfile
 import threading
-import typing
+from typing import Optional
 from itertools import chain
 
 COMMON_WSL_CMD_PATHS = (