[BUG] - Python Kubernetes library doesn't support CronJobs

[DilaraOflaz]

Describe the bug
Kubernetes library versions prior to 21.7.0 don't support CronJobs.

To Reproduce
Steps to reproduce the behavior:

1. In kubetools/setup.py modify line 59 to:

    'kubernetes==20.13.0',

2. Run pip install -e .[dev]
3. Run kubetools deploy ${NAMESPACE}.

Expected behavior
AttributeError: 'BatchV1Api' object has no attribute 'list_namespaced_cron_job'