This reverts commit 7c8f6cb9.

Rationale: https://lists.debian.org/debian-boot/2023/01/msg00203.html

Fix some issues reported by lintian

See merge request !2

Changes-By: lintian-brush
Fixes: lintian: uses-debhelper-compat-file
See-also: https://lintian.debian.org/tags/uses-debhelper-compat-file.html

Changes-By: lintian-brush
Fixes: lintian: package-uses-deprecated-debhelper-compat-version
See-also: https://lintian.debian.org/tags/package-uses-deprecated-debhelper-compat-version.html

Remove unnecessary constraints

See merge request !1

* Build-Depends: Drop versioned constraint on po-debconf.

Changes-By: deb-scrub-obsolete