check-presubmit: use subprocess.run

Fixing feedback from crrev.com/c/3877334, which isn't strictly related
to that change, but is still useful to clean up

BUG=None
TEST=`repo upload`

Change-Id: I1e183e174cc99dc9e309cc53fbde9f545eb8536f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3877525
Tested-by: George Burgess <gbiv@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
1 file changed