fix: validation now allows challengeType 27 (freeCodeCamp#59825)

Author: majestic-owl448

curriculum/schema/challenge-schema.js

@@ -156,7 +156,7 @@ const schema = Joi.object()
       otherwise: Joi.optional()
     }),
     certification: Joi.string().regex(slugWithSlashRE),
-    challengeType: Joi.number().min(0).max(26).required(),
+    challengeType: Joi.number().min(0).max(27).required(),
     checksum: Joi.number(),
     // TODO: require this only for normal challenges, not certs
     dashedName: Joi.string().regex(slugRE),