Fix some issues reported by lintian

Fix some issues reported by lintian

• Use secure copyright file specification URI. (insecure-copyright-format-uri)
• Use secure URI in Homepage field. (homepage-field-uses-insecure-uri)
• Bump debhelper from old 9 to 12. (package-uses-old-debhelper-compat-version)
• Set debhelper-compat version in Build-Depends. (uses-debhelper-compat-file)
• Change priority extra to priority optional. (priority-extra-is-replaced-by-priority-optional)
• Move transitional package php-propro-dev to oldlibs/optional per policy 4.0.1. (transitional-package-should-be-oldlibs-optional)
• Set upstream metadata fields: Bug-Database, Bug-Submit, Repository, Repository-Browse. (upstream-metadata-file-is-missing)

This merge proposal was created automatically by the Janitor bot.

You can follow up to this merge proposal as you normally would.

Build and test logs for this branch can be found at https://janitor.debian.net/lintian-fixes/pkg/php-propro/ca59a448-ba84-4626-bd34-8ae5bf7520f8.

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/.dwz/x86_64-linux-gnu/php-propro.debug

Control files of package php-propro: lines which differ (wdiff format)

• Homepage: http​://pecl.php.net/package/propro https​://pecl.php.net/package/propro

No differences were encountered between the control files of package **php-propro-dbgsym**

Control files of package php-propro-dev: lines which differ (wdiff format)

• Homepage: http​://pecl.php.net/package/propro https​://pecl.php.net/package/propro
• Priority: extra optional

You can also view the diffoscope diff (unfiltered).