Modernize supported distros list.
- Added: Fedora up until 35
- Added: AlmaLinux 8, Rocky Linux 8 (RHEL8-like )
- Added: Debian 11 (bullseye)
- Dropped official support for ancient distros: Debian 9, Ubuntu 16.04 LTS, Fedora before 33 (they are still likely to work, but not covered by CI)