docs: updated postman collection link

Author: ClarksonAdam

specification/validated-relationships-service-api.yaml

@@ -124,7 +124,7 @@ info:
     * is open access, so does not allow you to test authorisation
 
 
-    [![Run in Postman](https://run.pstmn.io/button.svg)](https://god.gw.postman.com/run-collection/34042403-24814c29-3493-40de-bb74-57e98eadaf1d?action=collection%2Ffork&source=rip_markdown&collection-url=entityId%3D34042403-24814c29-3493-40de-bb74-57e98eadaf1d%26entityType%3Dcollection%26workspaceId%3Dc2d4b94e-3492-48f4-ae19-e26bd5514da9)
+    [![Run in Postman](https://run.pstmn.io/button.svg)](https://app.getpostman.com/run-collection/18067099-d6d93fa6-55b2-4d98-9f82-d3d01638f262?action=collection%2Ffork&collection-url=entityId%3D18067099-d6d93fa6-55b2-4d98-9f82-d3d01638f262%26entityType%3Dcollection%26workspaceId%3Dd68c8af0-0a36-4e0a-b612-fe0ec8e284ca)
 
     ### Integration testing