Merge pull request #6594 from ulyssessouza/bump-docker-py-to-3.7.1

Bump docker-py version to 3.7.1

requirements.txt

@@ -3,7 +3,7 @@ cached-property==1.3.0
 certifi==2017.4.17
 chardet==3.0.4
 colorama==0.4.0; sys_platform == 'win32'
-docker==3.7.0
+docker==3.7.1
 docker-pycreds==0.4.0
 dockerpty==0.4.1
 docopt==0.6.2