Installing HPLIP 3.21

Hi, I try to install HPLIP 3.21. I installed the dependencies myself as suggest in Upgrading hplip in Zorin OS for Scanner.
the HP installer gives me the following error:

Following dependencies are not installed. HPLIP will not work if all REQUIRED dependencies are not installed and some of the HPLIP features will not work if OPTIONAL dependencies are not installed.
Package-Name         Component            Required/Optional   
libavahi-dev         scan                 REQUIRED            
reportlab            fax                  OPTIONAL            
Do you want to install these missing dependencies (y=yes*, n=no, q=quit) ? y

note: Installation of dependencies requires an active internet connection.
warning: Missing REQUIRED dependency: libavahi-dev (libavahi-dev)
warning: This installer cannot install 'libavahi-dev' for your distro/OS and/or version.
error: Installation cannot continue without this dependency. Please manually install this dependency and re-run this installer.

I tried
sudo apt install libavahi-dev
Paketlisten werden gelesen... Fertig
Abhängigkeitsbaum wird aufgebaut.
Statusinformationen werden eingelesen.... Fertig
E: Paket libavahi-dev kann nicht gefunden werden.
(can not be found)

What can I do?

There are several solutions proposed in this thread:

I am not sure how many may apply to you... But I hope something in there helps.

Yes, but these answers do not refer to the missing libavahi-dev.
It also seems to affect mint: Bug #1924871 “HPLIP 3.21.2 fails under Mint 20.1 on dependencies...” : Bugs : Ubuntu

The solution is to take an older software. You can check on the HP page which one your printer needs.