chore(requirements): update codecov lib to 2.0.3

See codecov/codecov-python@v1.6.3...v2.0.2

Author: mboersma

rootfs/dev_requirements.txt

@@ -5,7 +5,7 @@ coverage==4.0.3
 flake8==2.5.4
 
 # code coverage report at https://codecov.io/github/deis/workflow
-codecov==1.6.3
+codecov==2.0.3
 
 # mock out python-requests, mostly k8s
 # requests-mock==0.7.0