Fix some issues reported by lintian

Fix some issues reported by lintian

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

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Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/kodi-pvr-nextpvr/93db5937-b46d-4d60-a2d1-0cccedace0bf.

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/97/e7e89f97b751faa4d3dedd4671a14a10ed504b.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/9b/69444d3c4e3ff4a1d66cf906f4ee111b3e9956.debug

No differences were encountered between the control files of package **kodi-pvr-nextpvr**

Control files of package kodi-pvr-nextpvr-dbgsym: lines which differ (wdiff format)

• Build-Ids: 9b69444d3c4e3ff4a1d66cf906f4ee111b3e9956 97e7e89f97b751faa4d3dedd4671a14a10ed504b

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