Fix some issues reported by lintian

Fix some issues reported by lintian

• Trim trailing whitespace. (file-contains-trailing-whitespace)
• Bump debhelper from deprecated 9 to 12. (package-uses-deprecated-debhelper-compat-version)
• Set upstream metadata fields: Bug-Database, Bug-Submit. (upstream-metadata-file-is-missing, upstream-metadata-missing-bug-tracking)

This merge proposal was created automatically by the Janitor bot.

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/kodi-visualization-spectrum/f9b9acba-20b0-4e3a-b327-9716d23f68ec.

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 .changes but not in first

-rw-r--r--  root/root   /usr/lib/debug/.build-id/f1/4b90734ca4650024028d12d5da23167f0e1803.debug

Files in first .changes but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/26/d5008b6362a0e21c89c9d71357d2e30940dd55.debug

No differences were encountered between the control files of package **kodi-visualization-spectrum**

Control files of package kodi-visualization-spectrum-dbgsym: lines which differ (wdiff format)

• Build-Ids: 26d5008b6362a0e21c89c9d71357d2e30940dd55 f14b90734ca4650024028d12d5da23167f0e1803

You can also view the diffoscope diff (unfiltered).