Form required field label fails AAA contrast

[sangtrinh]

We're trying to hit AAA for a GoC site we're building however we've noticed that the style guide recommendations for the colour of the (required) label (#d3080c) fails the contrast requirement for AAA (it is 5.51 vs the required 7) on a pure white background. The working examples of this can be found here: https://wet-boew.github.io/v4.0-ci/demos/formvalid/formvalid-en.html. Any recommendations or thoughts on changing this? Changing this to (#820101) does make it pass, but we'd rather get direct feedback on how best to approach this and have a solution commonalised across wet.

[ghost]

Also related discussion: https://github.com/wet-boew/wet-boew/issues/7896

@duboisp @lisafast