Suggest a default commit message for eas build

[EvanBacon]

speedway 𝝠 eas build -p ios       
✔ Ensuring @expo-turtle/ejbtest10 is created on Expo

Warning! Your git working tree is dirty.
This operation needs to be run on a clean working tree, please commit all your changes before proceeding.
✔ Commit changes to git? … yes
? Commit message: › 

This should suggest something. IMO it would be nice for this to be formatted like a publish commit, so maybe Publish iOS <build number> or something like that. Mostly I don't care and I end up just doing wip