[DEVIALET PHANTOM I & II] - Release notes - DOS 2.21.2

This release requires Devialet app version 1.27 or later. It includes the following improvements compared with DOS 2.19.1:
- Enhanced Bluetooth (BLE) setup reliability
- Improved product visibility
- Updated Spotify Connect integration
- Optimized network performance
- Improved accessory management
- Faster firmware download speeds in China
- Additional bug fixes and enhancements