Merge branch 'hide_dockerhub_credentials_for_non_protected_branch' into v2.2.0

ExerciseChecker/.gitlab-ci/01_functions.yml

@@ -20,7 +20,10 @@
         - apk add curl
 
         # Init docker buildx
-        - docker login -u $DOCKER_REGISTRY_USER -p $DOCKER_REGISTRY_PASSWORD $DOCKER_REGISTRY
+        - |
+            if [ $CI_COMMIT_REF_PROTECTED == "true" ]; then
+                docker login -u $DOCKER_REGISTRY_USER -p $DOCKER_REGISTRY_PASSWORD $DOCKER_REGISTRY
+            fi
         - docker buildx create --use
 
         # Get version from package.json