ci: Re-enable python subtests in qtest migration suite

The migration compatibility tests have been running with the PYTHON
variable unset to avoid running a broken test. The faulty test has
since been removed, so we can enable the python tests once again.

Aside from the broken test, only one other test uses python and I have
been running it locally ever since, so this commit should not expose
any new bug.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250513133353.23022-2-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
1 file changed