Updated mediawiki/extensions
Project: mediawiki/extensions/Blackout  b8e2bcc42d534e91b894970b2ea078354e659515

Replaced some wfMsg* deprecated functions

Also register skin template classes, because it caused CI to fail.

Bug: T70750
Change-Id: Ie5eba6cbeeedc4900042c0a85fd9f94353ca4ec5