Update codecov from 2.1.5 to 2.1.6 (#372)

Author: pyup-bot

requirements-testing.txt

@@ -6,7 +6,7 @@ pytest-cov==2.10.0
 autopep8==1.5.3
 mypy==0.780
 py-spy==0.3.3
-codecov==2.1.5
+codecov==2.1.6
 tox==3.15.2
 mccabe==0.6.1
 pylint==2.5.3