replace a removed method is_ajax() in Django 4.0 with an alternative

[ghost]

form_valid() has already been fixed as below:

django-markdownx/markdownx/views.py

Line 76 in 52c9a1e

if self.request.headers.get('x-requested-with') == 'XMLHttpRequest':

But form_invalid() hasn't yet. The patch fixes it.

ref: #221

[josefdlange]

Bump! How can we work to get this merged in an a release cut?

[adi-]

done

[bellini666]

@adi- can we get a new release for the fix? I'm currently relying on installing this from git to for my django 4.1 projects

Oh, nvm, just saw that a new release as already made =P

[adi-]

It is published. version 4.0.0