manifest_utils_unittest: fix lints, mark as executable

BUG=b:301256174
TEST=Ran the test

Change-Id: I0713441195a128ff3fb8effb9179869928fcd383
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/4879498
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Tested-by: George Burgess <gbiv@chromium.org>
Commit-Queue: George Burgess <gbiv@chromium.org>
1 file changed