[PATCH] buildman: Fix full help for Python 3.8

[Simon Glass]

With Python versions older than 3.9 Buildman produces an error on
start-up. Fix this with a workaround for importlib.

There is already a workaround for v3.6 but I am not sure if that is still
functioning.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 tools/buildman/main.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Applied to u-boot-dm, thanks!