* Revert "fix: clean obsolete check 99.5.4.5.1, now handled by 5.3.4 (#215)"
This reverts commit 670c8c62f5.
We still want to verify the preexisting hashes in /etc/shadow,
even if the PAM configuration is correct for new passwords (5.3.4).
* Adapt 5.3.4, 99.5.4.5.1 and 99.5.4.5.2 to yescrypt