fix: make the default values strings

Author: imadbourouche

config/schemes/semantic_artefact_catalog.yml

@@ -590,8 +590,8 @@ themeTaxonomy:
   display: "general"
   label: "Theme Taxonomy"
   helpText: "Taxonomy themes of the catalog."
-  example: [http://vocabularies.unesco.org/thesaurus]
-  default: [http://vocabularies.unesco.org/thesaurus]
+  example: [ "http://vocabularies.unesco.org/thesaurus" ]
+  default: [ "http://vocabularies.unesco.org/thesaurus" ]
 
 distribution:
   display: "general"