Step exercise timer

Oct 19, 2023

v1.21.0 (2023-10-04)
Improvement:
- Some internal libraries have been upgraded.

v1.20.0 (2023-07-27)
Improvement:
- Added a dialog to change the volume of the guide sound.

v1.19.0 (2023-06-08)
Improvement:
- Added a themed app icon for Android 13 or later.

v1.18.0 (2023-02-03)
Improvement:
- Android 13 support has been improved.