CI: Visibly print trailing whitespace when static checks fail

GitHub Actions seems to be hiding colored whitespace, and after lots of
attempts I couldn't find a way to work it around.

So instead I'm using a perl expression to replace trailing spaces with
`·` and tabs with `<TAB>` in the ANSI colored diff output. This ensure
that they're visible, and they are properly colored as expected too.

(cherry picked from commit 266280ffca218ae1c86e6d83d9b67a16086148b8)

0 files changed, 0 insertions, 0 deletions