spec(transactional): bump version to 1.4.0

Author: jmoriarty-mc

spec/transactional.json

@@ -203,7 +203,7 @@
   },
   "swagger": "2.0",
   "info": {
-    "version": "1.3.3",
+    "version": "1.4.0",
     "title": "Mailchimp Transactional API",
     "contact": {
       "name": "API Support",