Fix some issues reported by lintian

Fix some issues reported by lintian

• Bump debhelper from old 12 to 13. (package-uses-old-debhelper-compat-version)

• Set upstream metadata fields: Bug-Database, Bug-Submit, Repository, Repository-Browse. (upstream-metadata-file-is-missing, upstream-metadata-missing-bug-tracking, upstream-metadata-missing-repository)

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/sscg/8ca1ce26-9052-45bb-b3a6-13f63aa19c23.

Debdiff

These changes affect the binary packages:

[The following lists of changes regard files as different if they have different names, permissions or owners.]

Files in second set of .debs but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/11/4cc25e316547cf0ed1bbd5887535b710badb47.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/6a/42845d4c7cf75e2351ad54ce0456ca2aabb95e.debug

No differences were encountered between the control files of package **sscg**

Control files of package sscg-dbgsym: lines which differ (wdiff format)

• Build-Ids: 6a42845d4c7cf75e2351ad54ce0456ca2aabb95e 114cc25e316547cf0ed1bbd5887535b710badb47

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