Fix some issues reported by lintian

Fix some issues reported by lintian

• Update standards version to 4.6.0, no changes needed. (out-of-date-standards-version)
• Set upstream metadata fields: Bug-Database, Bug-Submit, Contact. (upstream-metadata-missing-bug-tracking)
• Set field Upstream-Contact in debian/copyright.
• Remove obsolete field Contact from debian/upstream/metadata (already present in machine-readable debian/copyright).
• Update standards version to 4.6.1, no changes needed. (out-of-date-standards-version)
• Update standards version to 4.6.2, no changes needed. (out-of-date-standards-version)

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/85/85354511bbb20930269653d49839880e4c397e.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/3d/2e3eac1e5dd1e3be2df3bedbe68657bfb71f10.debug

No differences were encountered between the control files of package **libgnome-games-support-1-3**

Control files of package libgnome-games-support-1-3-dbgsym: lines which differ (wdiff format)

• Build-Ids: 3d2e3eac1e5dd1e3be2df3bedbe68657bfb71f10 8585354511bbb20930269653d49839880e4c397e

No differences were encountered between the control files of package **libgnome-games-support-1-dev**

No differences were encountered between the control files of package **libgnome-games-support-common**

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Build and test logs for this branch can be found at https://janitor.debian.net/run/4ac2ddcc-06cb-4eda-8298-b0ee47f726c3.