Fixed the datetimestamp warning.
requested to merge issue/socialfeed-3197190:3197190-warning-datetimesettimestamp-expects into 8.x-1.x
As per https://developer.twitter.com/en/docs/twitter-api/v1/data-dictionary/object-model/tweet "created_at": "Wed Oct 10 20:19:24 +0000 2018"
Closes #3197190