Fix some issues reported by lintian

Fix some issues reported by lintian

• Set upstream metadata fields: Bug-Database, Bug-Submit, Repository-Browse. (upstream-metadata-file-is-missing, upstream-metadata-missing-bug-tracking)
• 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 (out-of-date-standards-version)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/3e/7b4de27bb26c4c51fe414da6c578198849fdc1.debug
-rw-r--r--  root/root   /usr/lib/debug/.build-id/b8/bc4dcca4f3e1d8ac3d990bebea47e1fd9797bd.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/81/0f2f6c1dbc621d90ccd0c6a801afebe4ff1b95.debug
-rw-r--r--  root/root   /usr/lib/debug/.build-id/dd/973f0354efe95f0f833b67a1c506a4cf3600d7.debug

No differences were encountered between the control files of package **fcitx-libpinyin**

Control files of package fcitx-libpinyin-dbgsym: lines which differ (wdiff format)

• Build-Ids: 810f2f6c1dbc621d90ccd0c6a801afebe4ff1b95 dd973f0354efe95f0f833b67a1c506a4cf3600d7 3e7b4de27bb26c4c51fe414da6c578198849fdc1 b8bc4dcca4f3e1d8ac3d990bebea47e1fd9797bd

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This merge proposal was created by the Janitor bot, and it will automatically rebase or close this proposal as appropriate when the target branch changes. Any comments you leave here will be read by the Janitor's maintainers.

Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/fcitx-libpinyin/781abfb1-a307-439c-a266-d355d94adc29.