This way we can tweak the `fill` property of the SVG and style it with
CSS as the documented in the author's repo
(https://github.com/SamHerbert/SVG-Loaders)
> An icon's color can be manipulated by changing the fill attribute in
the SVG file.
For https://github.com/openfoodfoundation/openfoodnetwork/issues/3491
The spinjs-rails gem provides a CSS3 a spinning activity indicator. This commit removes the gem so we don't have to keep the gem up-to-date and uses the spinning-circles.svg which is used already in other places.
The spinjs spinner can be seen when viewing or editing taxonomies in /admin/taxonomies. It is loaded from the .ajaxStart call in app/assets/javascripts/admin/spree/progress.coffee
To test or restyle this spinner you can change the display property of the #progress element in app/assets/stylesheets/admin/components/progress.scss to 'block'.
