• update to material design
• comply to new android requirements, full support for android 12
• remove google tasks sync
• change folder selection method for SD sync and JSON backups
• remove internet permission: the app is now 100% offline

Technical:

• raise min SDK and target SDK (23 and 32)
• update libraries, migrate to androidx
• update gradle, ensure the app can build
• fix all tests
• remove old files, general code cleanup

Use f-droid or the play store to get a signed release version.