[3.11] gh-88496: Fix IDLE test hang on macOS (GH-104025) (#104027)

gh-88496: Fix IDLE test hang on macOS (GH-104025)

Replace widget.update() with widget.update_idletasks in two places.
(cherry picked from commit 4b27972f5f)

Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

Lib/idlelib/colorizer.py

@@ -310,7 +310,7 @@ def recolorize_main(self):
                     # crumb telling the next invocation to resume here
                     # in case update tells us to leave.
                     self.tag_add("TODO", next)
-                self.update()
+                self.update_idletasks()
                 if self.stop_colorizing:
                     if DEBUG: print("colorizing stopped")
                     return