Automate adding testers to Google Play Console Closed testing track #223

Given the difficulties with installing this app on Android 14+, consider automating the process of adding testers to Google Play Console Closed testing track via Google Group, as it has been done here.

Steps:

1. Create new Google Group
2. Google Play Console > app > Test and Release > Testing > Closed testing > track > Manage Track > Testers > Google Groups

   Email addresses
   Enter Google Group email addresses. Only users who are members of the Google Groups you specify will be able to join your test.

3. Add instructions with links Join on Android and _Join on the web) to README.md

An alternative would be to create on Open testing track and share URL here.