keybindings: Reset modifier-only-pressed on scroll

Since commit c255031b6d, we allow some modifier+scroll events to
pass through to Clutter to enable gnome-shell to handle them. That
action shouldn't trigger a modifier-only action at the same time, so
reset the corresponding tracking just like we do for modifier+click.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1695>

src/core/keybindings.c

@@ -2340,6 +2340,7 @@ meta_keybindings_process_event (MetaDisplay        *display,
     case CLUTTER_BUTTON_RELEASE:
     case CLUTTER_TOUCH_BEGIN:
     case CLUTTER_TOUCH_END:
+    case CLUTTER_SCROLL:
       keys->overlay_key_only_pressed = FALSE;
       keys->locate_pointer_key_only_pressed = FALSE;
       return FALSE;