Update MotionMark link on https://browserbench.org/index.html to MotionMark 1.3
<rdar://problem/120752839>
Pull request: https://github.com/WebKit/WebKit/pull/22558
Committed 272832@main (eaae00a07106): <https://commits.webkit.org/272832@main> Reviewed commits have been landed. Closing PR #22558 and removing active labels.