python: Use spaces, not tabs

python: Use spaces, not tabs

Python 3 doesn't allow mixing spaces and tabs in a script, contrarily to
Python 2.

Signed-off-by: Mathieu Bridon <bochecha@daitauha.fr>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>