Safari for iOS now supports USB and NFC for CTAP2

Hi @apowers313 ,

After seeing [yesterday's release notes from apple](https://developer.apple.com/documentation/ios_ipados_release_notes/ios_ipados_13_3_release_notes) I tested it out in our [demo-app](https://github.com/cedarcode/webauthn-rails-demo-app) at https://webauthn.cedarcode.com I can confirm that it's supported and working.