python: Stop using the Python 2 exception syntax

python: Stop using the Python 2 exception syntax

We could have made this compatible with Python 3 by using:

    except Exception as e:

But since none of this code actually uses the exception objects, let's
just drop them entirely.

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