Looks like libksba 1.6.1 is available for download at: https://gnupg.org/download/ , however tag is missing at: https://git.gnupg.org/cgi-bin/gitweb.cgi?p=libksba.git;a=summary

Package maintainer from PLD here. We still ship Qt4 and therefore provide pinentry qt4 for as long as it's supported. I have no problem with dropping it if it's no longer support, but last release still supported Qt4, there's no mention of dropping such support in NEWS and both code as well as configure.ac appear to still carry Qt4 support which is a bit confusing.