.github/workflows/editorconfig.yml: check indent_style

[zowoq]

When we first started with this editorconfig-checker only supported disabling the indentation check, upstream has since added support for disabling indent_size which would allow us to check only indent_style (spaces vs tabs).

indent_size would still be a bit disruptive to enable but I think indent_style would be fine.

check	errors	files in pkgs/*
Current	~700	~400
Current + indent_style	~2000	~550
Current + indent_style (with excludes)	~1400	~500
Current + indent_{size,style}	~60000	~1950

I'll fix everything outside pkgs (doc, nixos, etc) which is an extra ~250 errors in ~20 files.

[zowoq]

Hmm, I don't think I meant to switch this to a draft.