www/kiwix-tools: Update 3.5.0 → 3.7.0

Selected list of improvements:

• Improved kiwix-serve man page
• New --skipInvalid Kiwix Server command line option
• Fixed ZIM name vs Book name confusion in documentation

See also:
https://github.com/kiwix/kiwix-tools/releases/tag/3.6.0
https://github.com/kiwix/kiwix-tools/releases/tag/3.7.0

This is a maintainer update (olce.freebsd.ports@certner.fr).

Approved by: jrm (ports)
Approved by: emaste (mentor)