Don't use `--whitespace=fix` for changes on `deps/`

[mmarchini]

Not sure if there's an easy way to do it, but we had recent CI failures on master and v12 because --whitespace=fix made invalid changed to V8 test fixtures. Since we sync deps/ from upstream projects, avoiding unwanted whitespace changes there is probably a good idea.

[targos]

I wonder if we shouldn't just remove the flag altogether. There are also some tools where we probably shouldn't apply it and for the rest, code review can spot the rare case where people introduce extra whitespaces.

[codebytere]

I think i'd be in favor of removing it altogether as well - happy to take this if that's the direction we wanna go!