Every day is too much noise - we really only need this
- When a string gets changed in the source translation, in which case this
workflow gets triggered automatically anyway.
- Before we do a new release (this doesn't automatically happen, but the
workflow can be triggered manually if needed).
For now, reduce the frequency of the daily job to pull new translations from
Crowdin: now it'll only happen on Tuesdays and Fridays (just an arbitrary
choice).
