Sync the debian packaging into apkg format

- Drop the versioned dependency on pcre2 (the oldest still supported Debian has
  pcre2 10.22 and the oldest still supported Ubuntu has pcre2 10.31)
- Update the symbols file up to upstream 2.0.7 version
- Update the yanglint autopkgtest for libyang2 packaging
diff --git a/distro/pkg/deb/copyright b/distro/pkg/deb/copyright
index 0fdade1..03af3c3 100644
--- a/distro/pkg/deb/copyright
+++ b/distro/pkg/deb/copyright
@@ -47,6 +47,11 @@
  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+Files: debian/*
+Copyright: 2018 by David Lamparter
+	   2020-2021 Ondřej Surý
+License: BSD-3-clause
+
 License: BSD-3-clause
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met: