Fix graphql selection sets

Author: abnegate

templates/graphql/docs/example.md.twig

@@ -16,7 +16,7 @@ mutation {
         {%~ for definition in spec.definitions %}
         {%~ if definition.name == method.responseModel %}
         {%~ for property in definition.properties | filter(p => p.required) %}
-        {{ property.name | caseCamel }}{% if not loop.last %},{% endif %}
+        {{ property.name | caseCamel }}
 
         {%~ endfor %}
         {%~ if definition.additionalProperties %}