White space in CI

Devs As you'll see from this pipeline record https://gitlab.haskell.org/ghc/ghc/-/merge_requests/7105/pipelines CI consistently fails once a single commit has trailing whitespace, even if it is fixed in a subsequent commit - dce2054d https://gitlab.haskell.org/ghc/ghc/-/commit/dce2054d44ea60bdde6409050284fbbc... introduced trailing whitespace - 6411223c https://gitlab.haskell.org/ghc/ghc/-/commit/6411223cd3977c92d01b09b55a455d8d... removed it again. - but all subsequent pipelines fail This came as a big surprise. It doesn't make sense to lint each individual commit. Let's just lint the final version! (I will squash them in due course, but I didn't want to lose my work-in-progress history.) Simon