Fix some issues reported by lintian

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Fixes: lintian: out-of-date-standards-version
See-also: https://lintian.debian.org/tags/out-of-date-standards-version.html

Remove unnecessary constraints

* Build-Depends: Drop versioned constraint on libgtk-3-dev.

Changes-By: deb-scrub-obsolete

Fix some issues reported by lintian

Remove obsolete field Name from debian/upstream/metadata (already present in machine-readable debian/copyright).

Changes-By: lintian-brush

Changes-By: lintian-brush
Fixes: lintian: vcs-field-not-canonical
See-also: https://lintian.debian.org/tags/vcs-field-not-canonical.html