travis build is too frequent

Seems like the travis build robot's cron is telling this repo to be built every day (is that correct?) Maybe we should go back to a weekly build cadence so that this repo's size doesn't explode.

Start by inspecting this repository's Travis build and cron configuration to verify whether builds are scheduled daily. Change the cadence to weekly if confirmed, then verify that scheduled builds no longer run every day.

Written by the indexing model from the issue text.