Bump docker-py version to latest RC

Signed-off-by: Joffrey F <[email protected]>

requirements.txt

@@ -1,6 +1,6 @@
 PyYAML==3.11
 cached-property==1.2.0
-docker-py==1.7.0rc2
+docker-py==1.7.0rc3
 docopt==0.6.1
 enum34==1.0.4
 git+https://github.com/d11wtq/dockerpty.git@29b1394108b017ef3e3deaf00604a9eb99880d5e#egg=dockerpty