Update coverage from 4.4b1 to 4.4.1

Author: pyup-bot

{{cookiecutter.project_slug}}/requirements.txt

@@ -4,7 +4,7 @@ appdirs==1.4.3
 Babel==2.5.0
 colander==1.3.3
 configparser==3.5.0
-coverage==4.4b1
+coverage==4.4.1
 docutils==0.13.1
 execnet==1.4.1
 funcsigs==1.0.2