Updated mediawiki/extensions
Project: mediawiki/extensions/MultimediaViewer  c1fb20fedbc70649c386d1fc648cf2fb8b9d2895

Add checkered background to make  black-on-transparent images visible

Bug: 57620
Change-Id: Ibabbb6d64f9d02ff5b94431a431ebb5222e344d7
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/284