Fix some issues reported by lintian

See merge request !1

Changes-By: lintian-brush
Fixes: lintian: out-of-date-standards-version
See-also: https://lintian.debian.org/tags/out-of-date-standards-version.html

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

Changes-By: lintian-brush
Fixes: lintian: tab-in-license-text
See-also: https://lintian.debian.org/tags/tab-in-license-text.html

Closes: #957409

Closes: #941408

Closes: #882293