The `--format` option for `git ls-tree` was introduced in git v2.36 and
hence gclient breaks for lower git versions.
Change-Id: I02750904aa78bb5fd5f3f57dc2ad42e355fa4a42
Bug: 1471241
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4765682
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>