Updates a function.
Each time the function is updated,
revision increments by 1.
The existing revision must be passed when updating the function.
This ensures you're working with the latest version of the function
and prevents unintended overwrites.
You can only call this method when authenticated as a Wix app or Wix user identity.
This method doesn't return any custom errors, but may return standard errors. Learn more about standard Wix errors.