Squash merging is only of the feature branch to master. If your feature branch makes it through code review and acceptance and you still need to update the typo, then you make the commit to master directly.

It would be great if we could be perfect, but sometimes small commits to master do have to happen. All we do is make sure we subject every feature to code review and acceptance before it gets to master. If it slips through, then it's technically a new change request in our eyes