chore(dev_requirements): use deis/requests-mock fork

Author: mboersma

rootfs/dev_requirements.txt

@@ -8,8 +8,8 @@ flake8==3.3.0
 codecov==2.0.5
 
 # mock out python-requests, mostly k8s
-# requests-mock==1.0.0
-git+https://github.com/helgi/requests-mock.git@class_adapter#egg=request_mock
+# requests-mock==1.3.0
+git+https://github.com/deis/requests-mock.git@class_adapter#egg=request_mock
 
 # tail a log and pipe into tbgrep to find all tracebacks
 tbgrep==0.3.0