Updated mediawiki/skins
Project: mediawiki/skins/Nimbus  b9973cf5d2a0dff8871cedee6d18f5b0d5b722ad

Avoid usage of {{SITENAME}}

Spotted by Purodha Blissenbach and reported at
https://translatewiki.net/wiki/Thread:Support/About_MediaWiki:Nimbus-pages-can-be-edited/ksh

Change-Id: I084460dd63b56028f37e630af03664d1bdd95ce6