Describe the bug

The HTML for the feedback messages redundantly uses role="alert", aria-live="assertive" and aria-atomic="true"
Elements with the role alert have an implicit aria-live value of assertive, and an implicit aria-atomic value of true.
https://www.w3.org/TR/wai-aria-1.1/#alert

I think this also makes using aria-live="polite" irrelevant.

Steps to reproduce the bug

1. Go to https://bootstrap-vue.org/docs/components/form-group
2. Trigger the feedback messages in the demo component
3. Inspect the rendered markup

Versions

Libraries:

• BootstrapVue: 2.21.2

Demo link

https://bootstrap-vue.org/docs/components/form-group

Additional context

I have not validated that this is an issue with assistive technology, only with the aria specifications.