Form validate prop should not be passed down to html form element

[stuller]

The doc site has a js error caused by the validate prop getting passed down to the html form element:

Fix should just be adding validate to the blacklist in this line like so:
const othersFiltered = blacklist(others, "onSubmit", "validate");

That will prevent it from getting added to the form dom element, since it only gets othersFiltered.
We are already using this to populate the noValidate attribute on the dom element, so removing this should not disrupt functionality.

You'll need to update snapshot test as well before putting in a PR.