updating chrome/chromedriver listing, ref #668

What does this Merge Request do?

This updates the listing in prepare.md for Chrome and Chromedriver. Somewhere along the way, the versioning between the two have aligned, and our listed versions are out of date. This MR updates the listing.

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.

Closes #668 (closed)

V2 of !1244 (closed) which had some problemos.