Add tests/config.yml file to skip sanity compile tests for unsupported versions of Python

[alisonlhart]

Add a tests/config.yml file to skip unsupported Python versions so ansible-test sanity is clean in the Automation Hub import pipeline.
In the last release (v5.2.0) there were Python 2.7 and 3.5 errors.
See https://github.com/ansible/ansible/blob/devel/test/lib/ansible_test/config/config.yml.