try to fix joi problem

backend/utils/schema.js

@@ -22,10 +22,9 @@ var validGet = Joi.object({
     after: Joi.date().timestamp()
 });
 
-var validURL = Joi.object({
-    title: Joi.string()
+var validURL = Joi.string()
         .regex(/^[a-z0-9áàâäãåçéèêëíìîïñóòôöõúùûüýÿæœ._'-]{1,60}\d{4}$/) //
-        .required(),
-});
+        .required()
+;
 
 module.exports = { newToucan, validTitle, validId, validURL, validGet };
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