Fix class registry

Author: tvdijen

classes/.gitkeep

@@ -35,6 +35,7 @@
         "ext-spl": "*",
 
         "simplesamlphp/assert": "~1.8.1",
+        "simplesamlphp/composer-xmlprovider-installer": "~1.0.2",
         "symfony/finder": "~6.4.0"
     },
     "require-dev": {