Update composer.json to add required modules

opigno_skills_system is part of this module.

Closes #3460021

composer.json

@@ -5,7 +5,9 @@
   "homepage": "http://drupal.org/project/opigno_module",
   "license": "GPL-2.0+",
   "require": {
-      "drupal/pdf": "1.x-dev#ec8d13d"
+      "drupal/pdf": "^1.2",
+      "drupal/h5p": "^2.0@alpha",
+      "drupal/opigno_group_manager": "^3.1"
   },
   "minimum-stability": "dev"
 }