Fix some issues reported by lintian

Fix some issues reported by lintian

• Set upstream metadata fields: Bug-Database, Bug-Submit. (upstream-metadata-missing-bug-tracking)
• Set upstream metadata fields: Repository. (upstream-metadata-missing-repository)
• 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 (out-of-date-standards-version)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/6c/6b6f5379d2be34e213ae0e4174da2d691f72a7.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/5b/2a21d9fa40059dc092f75c83fc22211e76b22b.debug

No differences were encountered between the control files of package **shairport-sync**

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

• Build-Ids: 5b2a21d9fa40059dc092f75c83fc22211e76b22b 6c6b6f5379d2be34e213ae0e4174da2d691f72a7

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