Open Beta v8.4 | Please help testing and hardening the upcoming release

All info can be found on GitHub: https://github.com/MichaIng/DietPi/issues/5452

Many thanks to all testers :heart:!

DietPi v8.4 has been released: https://github.com/MichaIng/DietPi/pull/5460

Release notes: https://dietpi.com/docs/releases/v8_4/