Bug#802889: please don't depend on all python3 versions

[Matthias Klose]

Package: python3-coverage
Version: 3.7.1+dfsg.1-1+b2
Severity: important
Tags: sid stretch
please don't depend on all python3 versions, forcing the installation of all 
python versions shouldn't be enforced for a module.

$ apt-cache show python3-coverage | grep Depends
Depends: python3-pkg-resources, python3 (<< 3.6), python3 (>= 3.4~), python3.4, 
python3.5, libc6 (>= 2.4)