Merge branch 'gc_patch_setup_py_for_older_airflow' into 'master'

Yan Sushchynski [EPAM/GC]requested to merge
cherry-pick-29c1335a into release/0.23

Update setup.py for supporting older versions of Airflow

See merge request !66 (merged)

(cherry picked from commit 29c1335a)

5e2898cc Update setup.py 148cf59b Update setup.py

Merge request reports