fix requirements

backend/requirements_dev.txt

 atomicwrites==1.3.0
 attrs==19.1.0
 coverage==4.5.3
-cycler=0.10.0
+cycler==0.10.0
 Django==2.2.1
 django-cors-headers==3.0.2
 django-environ==0.4.5
@@ -12,7 +12,7 @@ djangorestframework-jwt==1.11.0
 entrypoints==0.3
 flake8==3.7.7
 importlib-metadata==0.18
-kiwisolver=1.1.0
+kiwisolver==1.1.0
 mccabe==0.6.1
 more-itertools==7.0.0
 packaging==19.0