LAKITU: Increment milestone number to m97

BUG=b/195987566
TEST=presubmit, check milestone number
RELEASE_NOTE=None

Change-Id: Id9d64c8486d5758746aa39f7c52135613b81f990
Reviewed-on: https://cos-review.googlesource.com/c/third_party/overlays/chromiumos-overlay/+/20970
Reviewed-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>