fix(aria-allowed-attr): allow aria-required on role=slider

[straker]

Tested in VO/Safari, JAWS/Chrome, and NVDA/Firefox.

Closes: #4027

[CLAassistant]

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1 out of 2 committers have signed the CLA.

✅ straker
❌ Steven Lambert

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[straker]

Going to open this again with the correct email for license.