[MBN-2763] Update the version number so that recent changes to the Swagger.json will also replicate to the Marketing API reference site.

Author: kaisma-penntitley

spec/marketing.json

@@ -752,7 +752,7 @@
     },
     "swagger": "2.0",
     "info": {
-        "version": "3.0.74",
+        "version": "3.0.75",
         "title": "Mailchimp Marketing API",
         "contact": {
             "name": "Mailchimp API Support",