[bug] Keyboard layout applet not updated on layout switch using shortcut

[NChechulin]

Cosmic-applets version: 0.1.0~1731341110~24.04~09062c1

Specific applet that this is regarding (if applicable): keyboard layout

Issue/Bug description:
After adding multiple keyboard layouts (different languages), I edited the /.config/cosmic/com.system76.CosmicComp/v1/xkb_config by adding multiple keyboard layout switch methods (options: Some(",grp:win_space_toggle,grp:caps_toggle,grp:alt_shift_toggle"),). When I use one of the shortcuts, the layout changes (i.e. I can type in different language), but the applet does not update.

Steps to reproduce:

1. add multiple keyboard layouts
2. add keyboard switch shortcuts by editing ~/.config/cosmic/com.system76.CosmicComp/v1/xkb_config
3. use one of the shortcuts
4. the language displayed on the applet would not change

[ids1024]

pop-os/cosmic-comp#660 will be needed to make the applet work more correctly. Then this should behave as expected.