Python doesn't care either way as long as indentation is consistent (though there's a common misunderstanding that Python cares). However PEP-8 specifies that code should be indented using 4 spaces and editors should be configured to render tabs as 8 spaces (likely to make mixed tabs & spaces really obvious). But PEP-8 also specifies that code should follow whatever is the coding standard in a given project.
IOW, Python is actually far more pragmatic than most people (including most Python programmers) think. It just has a culture that strongly advocates following the rules (i.e. PEP-8 and PEP-20).