Use composer:v1

Author: JeroenDeDauw

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
         with:
           php-version: ${{ matrix.php }}
           extensions: mbstring, intl
-          tools: composer
+          tools: composer:v1
 
       - name: Cache MediaWiki
         id: cache-mediawiki
@@ -84,7 +84,7 @@ jobs:
         with:
           php-version: '7.4'
           extensions: mbstring
-          tools: composer, cs2pr
+          tools: composer:v1, cs2pr
 
       - name: Cache MediaWiki
         id: cache-mediawiki