We are currently working with GitHub to move all of our customers who use Travis CI via OAuth from GitHub Services to webhooks.
GitHub Services were used initially to connect your repository at Travis CI with GitHub.
GitHub Services are currently deprecated and will stop delivering the events we need to run your builds on January 31st, 2019.
We expect that this work will take some time – at least into next week. During this time, if your repository was connected with Travis CI using GitHub services, you may notice a new webhook being set up.