Coveralls doesn't work

[muschellij2]

Getting pandoc error for coveralls badge

[![Coverage Status](https://img.shields.io/coveralls/muschellij2/mimosa.svg)](https://coveralls.io/r/muschellij2/mimosa?branch=master)

pandoc: Could not fetch https://img.shields.io/coveralls/muschellij2/mimosa.svg
TlsExceptionHostPort (HandshakeFailed Error_EOF) "img.shields.io" 443
Error: pandoc document conversion failed with error 67

when using img.shields.io from use_coverage.

When using the coveralls badge, this doesn't happen:

[![Coverage status](https://coveralls.io/repos/github/muschellij2/mimosa/badge.svg)](https://coveralls.io/r/muschellij2/mimosa?branch=master)

there no error. Same for if you put a branch:

[![Coverage status](https://coveralls.io/repos/github/muschellij2/mimosa/badge.svg?branch=master)](https://coveralls.io/r/muschellij2/mimosa?branch=master)

Submitting PR