Fix some issues reported by lintian

Fix some issues reported by lintian

• Update watch file format version to 4. (older-debian-watch-file-standard)
• Bump debhelper from old 12 to 13. (package-uses-old-debhelper-compat-version)
• Set upstream metadata fields: Bug-Database, Bug-Submit, Repository-Browse. (upstream-metadata-file-is-missing, upstream-metadata-missing-bug-tracking)
• Update standards version to 4.6.1, 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 (out-of-date-standards-version)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/15/5e5599f48f3a378df8f3f8fd96e2decbaeb899.debug
-rw-r--r--  root/root   /usr/lib/debug/.build-id/72/ce2c5edd00d74f6afdd7472f341552df3d4723.debug

Files in first set of .debs but not in second

-rw-r--r--  root/root   /usr/lib/debug/.build-id/03/3d86d502d27bef7291911b08de386b5cc35bba.debug
-rw-r--r--  root/root   /usr/lib/debug/.build-id/67/8e1815246ea4e24de2d5174ec5886c997efd28.debug

No differences were encountered between the control files of package **libbiniou-ocaml**

Control files of package libbiniou-ocaml-dbgsym: lines which differ (wdiff format)

• Build-Ids: 033d86d502d27bef7291911b08de386b5cc35bba 155e5599f48f3a378df8f3f8fd96e2decbaeb899

Control files of package libbiniou-ocaml-dev: lines which differ (wdiff format)

• Depends: libbiniou-ocaml-k99n8, libeasy-format-ocaml-dev-sajs5, ocaml-4.13.1, libc6 (>= 2.33) 2.35)

Control files of package libbiniou-ocaml-dev-dbgsym: lines which differ (wdiff format)

• Build-Ids: 678e1815246ea4e24de2d5174ec5886c997efd28 72ce2c5edd00d74f6afdd7472f341552df3d4723

You can also view the diffoscope diff (unfiltered).

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/biniou/449f9d40-32da-48d8-9243-927be889c031.