ci: remove unnecessary config.json

This file is only necessary in special cases. For this plugin it is
enough to rely on the automatic configuration done in the Learnweb
workflows.

Author: dlmsr

.github/workflows/config.json

@@ -2,6 +2,5 @@ name: Moodle Plugin CI
 on: [ push, pull_request ]
 
 jobs:
-  call:
-    name: ""
+  call-moodle-ci:
     uses: learnweb/moodle-workflows-learnweb/.github/workflows/moodle-ci.yml@main