tests: update EXTRA_DIST of Python bindings

tests: update EXTRA_DIST of Python bindings

This list is out of date, causing "make dist" to fail.

Sync the list of distributed files with the actual files.

Change-Id: Iedef7411c691689eb6a0505b4ea29d0f319f6860
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1242
Tested-by: jenkins
Reviewed-by: Jonathan Rajotte Julien <jonathan.rajotte-julien@efficios.com>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>