Update motor from 1.2.2 to 2.0.0

Author: pyup-bot

requirements-dev.txt

@@ -8,7 +8,7 @@ coverage==4.5.2
 docker==3.7.0
 flake8==3.7.5
 ipdb==0.11
-motor==1.2.2
+motor==2.0.0
 pytest-cov==2.5.1
 pytest-sugar==0.9.1
 pytest==4.2.0