Simple-icons: Update Bootstrap

[PeterShaggyNoble]

Name: Bootstrap
Official resources for icon and color: https://v5.getbootstrap.com/

As pointed out in Templarian/MaterialDesign#5238, Bootstrap have a new logo; an SVG can be found in the header of the page linked above. However, this blog entry suggests that they won't be rolling it out completely until they get to a stable release of v5 so we shouldn't update it just yet but rather keep an eye on things and update when they do.

[adamrusted]

Bootstrap seem to be using the new logo on website / socials now, despite the fact v5 is still in beta. Worth pushing the new version of the logo yet?

[fbernhart]

I would be in favour of updating it. @simple-icons/maintainers what do you think?

[service-paradis]

I agree, looks like they use it officially everywhere!