Fix installMediaWiki.sh

Author: JeroenDeDauw

.github/workflows/installMediaWiki.sh

@@ -3,7 +3,7 @@
 MW_BRANCH=$1
 EXTENSION_NAME=$2
 
-wget https://github.com/wikimedia/mediawiki/archive/$MW_BRANCH.tar.gz -nv
+wget "https://github.com/wikimedia/mediawiki/archive/refs/heads/$MW_BRANCH.tar.gz" -nv
 
 tar -zxf $MW_BRANCH.tar.gz
 mv mediawiki-$MW_BRANCH mediawiki