Updated coverage badge to codecov

README.md

@@ -1,6 +1,6 @@
 [![Package versioning](https://img.shields.io/pypi/v/nltools.svg)](https://pypi.org/project/nltools/)
 [![Build Status](https://api.travis-ci.org/cosanlab/nltools.png)](https://travis-ci.org/cosanlab/nltools/)
-[![Coverage Status](https://coveralls.io/repos/github/cosanlab/nltools/badge.svg?branch=master)](https://coveralls.io/github/cosanlab/nltools?branch=master)
+[![codecov](https://codecov.io/gh/cosanlab/nltools/branch/master/graph/badge.svg)](https://codecov.io/gh/cosanlab/nltools)
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/625677967a0749299f38c2bf8ee269c3)](https://www.codacy.com/app/ljchang/nltools?utm_source=github.com&utm_medium=referral&utm_content=ljchang/nltools&utm_campaign=Badge_Grade)
 [![Documentation Status](https://readthedocs.org/projects/neurolearn/badge/?version=latest)](http://neurolearn.readthedocs.io/en/latest/?badge=latest)
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.2229813.svg)](https://doi.org/10.5281/zenodo.2229813)