Changed version number to 9.2

TBR=hablich@chromium.org, vahl@chromium.org

Change-Id: I6c77e5de7a7c0222f01ee237f125a97538dd8cc6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2814558


Reviewed-by: Lutz Vahl <vahl@chromium.org>
Commit-Queue: Lutz Vahl <vahl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73866}