Fix some issues reported by lintian

Fix some issues reported by lintian

• Remove 2 obsolete maintscript entries in 1 files.
• Bump debhelper from old 11 to 13. (package-uses-old-debhelper-compat-version)
• Set debhelper-compat version in Build-Depends. (uses-debhelper-compat-file)
• Set upstream metadata fields: Repository, Repository-Browse. (upstream-metadata-file-is-missing, upstream-metadata-missing-repository)
• Update standards version to 4.6.0, no changes needed. (out-of-date-standards-version)
• Avoid explicitly specifying -Wl,--as-needed linker flag. (debian-rules-uses-as-needed-linker-flag)
• Set upstream metadata fields: Repository-Browse.
• 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 (out-of-date-standards-version)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 (out-of-date-standards-version)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/5e/cff67834f33e5737e871c184ad5efdd0894e4e.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/8e/16edaba9504485180855b252d5aa57c498285b.debug
-rwxr-xr-x  root/root   DEBIAN/postinst
-rwxr-xr-x  root/root   DEBIAN/postrm
-rwxr-xr-x  root/root   DEBIAN/preinst
-rwxr-xr-x  root/root   DEBIAN/prerm

Control files of package notification-daemon: lines which differ (wdiff format)

• Depends: libatk1.0-0 (>= 1.12.4), libc6 (>= 2.34), libcairo-gobject2 (>= 1.10.0), libcairo2 (>= 1.10.0), libgdk-pixbuf-2.0-0 (>= 2.22.0), libglib2.0-0 (>= 2.37.3), libgtk-3-0 (>= 3.19.12), libharfbuzz0b (>= 0.6.0), libpango-1.0-0 (>= 1.14.0), libx11-6 libpangocairo-1.0-0 (>= 1.14.0), libx11-6, zlib1g (>= 1:1.1.4)

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

• Build-Ids: 8e16edaba9504485180855b252d5aa57c498285b 5ecff67834f33e5737e871c184ad5efdd0894e4e

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Build and test logs for this branch can be found at https://janitor.debian.net/run/1f492203-09a9-46c6-b2b3-a4c7bf9b2aec.