Update to Bulma-1.0.1

[bpepple]

Looks like Bulma finally released 1.0.0.

https://github.com/jgthms/bulma/releases/tag/1.0.0

[hedyhli]

With v1.0.0 Bulma has its own theme variables as well as CSS-only variable customization support without the need of configuring them in BULMA_SETTINGS. I wonder if it's possible to retain backwards-compatibility on django-simple-bulma's side while allowing users who wishes to upgrade, use Bulma v1.0.0.

Note also, that the way django-simple-bulma implements BULMA_SETTINGS (by setting variables in sass then @import Bulma) is no longer recommended.

[intp1]

Looking forward to the updating to v1.0 of django-simple-bulma, especially the 'Dark Mode'.