Broken css in button styles file

[kirchsuSICKAG]

Describe the bug

With following PR #1928 a bug was added to the new shoelace version 2.15.0.
In the file button.style.ts line 593 the css selector was changed from
:host(.sl-button-group__button[checked]) {
to
:host([data-sl-button-group__button[checked]]) {

The new selector is no longer a valid css selector, which leads to that the followed css is no longer applied and so the right focus border is not shown (see screenshot)

To Reproduce

Steps to reproduce the behavior:

1. Go to https://codepen.io/kirchsuSICKAG/pen/OJGEEqO or to the button-group page of shoelace https://shoelace.style/components/button-group
2. Tab to the first sl-button so it is getting focus
3. Have a look at the applied styling of the focused button
4. There is not styling applied although because of this line :host([data-syn-button-group__button--focus]), there should be an applied styling

Screenshots

Browser / OS

• OS: Mac
• Browser: Chrome
• Browser version: 123.0.6312.105

Additional information

The bug can be fixed by changing line 593 of the button.style.ts to
:host([data-syn-button-group__button][checked]) {

[KonnorRogers]

Fixed in #1975