test_that: fix typo in usage string.

BUG=None
TEST=test_that --help shows no typo.

Change-Id: I78c1b3619095842c38a4abeb39c4acb95850dbed
Reviewed-on: https://chromium-review.googlesource.com/195500
Commit-Queue: Jorge Lucangeli Obes <jorgelo@chromium.org>
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
1 file changed