chore(dev_requirements): update codecov to v2.0.9

See codecov/codecov-python@v2.0.5...v2.0.9

Author: mboersma

rootfs/dev_requirements.txt

@@ -5,7 +5,7 @@ coverage==4.3.4
 flake8==3.3.0
 
 # code coverage report at https://codecov.io/github/deis/controller
-codecov==2.0.5
+codecov==2.0.9
 
 # mock out python-requests, mostly k8s
 # requests-mock==1.3.0