Change priority extra to priority optional.

Changes-By: lintian-brush
Fixes: lintian: priority-extra-is-replaced-by-priority-optional
See-also: https://lintian.debian.org/tags/priority-extra-is-replaced-by-priority-optional.html
2 jobs for lintian-fixes in 38 seconds
Status Name Job ID Coverage
  Build Pkgsrc
passed build_pkgsrc:buster #35836

00:00:09

 
  Build Pkg
passed build_pkg:buster:amd64 #35837
amd64

00:00:29