debian: call dh_installsysusers

From debhelper 14 it'll be called automatically
4 jobs for master in 1 minute (queued for 4 seconds)
Status Name Job ID Coverage
  Build Pkgsrc
passed build_pkgsrc:bullseye #38172

00:00:25

 
  Build Pkg
passed build_pkg:bullseye:amd64 #38173
amd64

00:00:24

 
  Upload Pkg
passed upload_pkg #38175

00:00:10

passed upload_pkg #38174

00:00:05