awx.main.tasks: Remove reference to unimport six

d4c3c08 re:introduced the use of six that has been removed by daeeaf4.
This lead to ""NameError: name 'six' is not defined"". This commit fixes
the issue.

Signed-off-by: Yanis Guenane <yguenane@redhat.com>

awx/main/tasks.py

@@ -468,7 +468,7 @@ def awx_periodic_scheduler():
             try:
                 job_kwargs = schedule.get_job_kwargs()
                 new_unified_job = schedule.unified_job_template.create_unified_job(**job_kwargs)
-                logger.info(six.text_type('Spawned {} from schedule {}-{}.').format(
+                logger.info('Spawned {} from schedule {}-{}.'.format(
                     new_unified_job.log_format, schedule.name, schedule.pk))
 
                 if invalid_license: