Update django-environ from 0.4.1 to 0.4.3

Author: pyup-bot

project/requirements/base.txt

@@ -5,7 +5,7 @@ django-jinja==2.3.0
 markupsafe==1.0
 
 # Configuration
-django-environ==0.4.1
+django-environ==0.4.3
 django-secure==1.0.1
 whitenoise==3.2.2