Description of problem:
Perl Net::LibIDN supports only IDNA 2003, the first generation of internationalized domain names. Perl Net::LibIDN uses GNU libidn as backend library, which states that GNU libidn2 is the successor of GNU libidn. As of writing, GNU libidn has been removed from the first Linux distributions, such as CentOS Stream 9 (upstream of Red Hat Enterprise Linux 9).

While GNU libidn2 provides a compatibility layer for GNU libidn, it doesn't seem to be easily possible to build Net::LibIDN against GNU libidn2, because Net::LibIDN doesn't provide only encoding and decoding of internationalized domain names, but also various intermediate GNU libidn methods.

Thus the proper perl answer to that is Net::LibIDN2 using GNU libidn2 as backend, which comes with a IDNA 2008 and TR46 implementation – and that's why I suggest to switch from Net::LibIDN to Net::LibIDN2.

Upstream report: https://gitlab.com/amavis/amavis/-/issues/83

Version-Release number of selected component (if applicable):
amavis-2.12.2-3.fc36
amavis-2.12.2-3.el9

Actual results:
Dependency on perl(Net::LibIDN).

Expected results:
Dependency on perl(Net::LibIDN2).

Additional info:
I've suggested https://gitlab.com/amavis/amavis/-/merge_requests/89 to upstream, however Debian doesn't seem to have Net::LibIDN2 packaged yet, so the CI fails. The patch proposal could be easily migrated to 2.12 stable series.