docs: replace travis badge with gh actions in readme

Author: cmdoret

README.md

@@ -1,5 +1,5 @@
 ### tinycov
-[![PyPI version](https://badge.fury.io/py/tinycov.svg)](https://badge.fury.io/py/tinycov) [![Build Status](https://travis-ci.com/cmdoret/tinycov.svg?branch=master)](https://travis-ci.com/cmdoret/tinycov) [![codecov](https://codecov.io/gh/cmdoret/tinycov/branch/master/graph/badge.svg)](https://codecov.io/gh/cmdoret/tinycov) [![Codacy Badge](https://app.codacy.com/project/badge/Grade/7878334fde574216bea3efd9a91b00fc)](https://www.codacy.com/gh/cmdoret/tinycov/dashboard?utm_source=github.com&utm_medium=referral&utm_content=cmdoret/tinycov&utm_campaign=Badge_Grade) [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
+[![PyPI version](https://badge.fury.io/py/tinycov.svg)](https://badge.fury.io/py/tinycov) [![build](https://github.com/cmdoret/tinycov/actions/workflows/python-tests.yml/badge.svg)](https://github.com/cmdoret/tinycov/actions/workflows/python-tests.yml) [![codecov](https://codecov.io/gh/cmdoret/tinycov/branch/master/graph/badge.svg)](https://codecov.io/gh/cmdoret/tinycov) [![Codacy Badge](https://app.codacy.com/project/badge/Grade/7878334fde574216bea3efd9a91b00fc)](https://www.codacy.com/gh/cmdoret/tinycov/dashboard?utm_source=github.com&utm_medium=referral&utm_content=cmdoret/tinycov&utm_campaign=Badge_Grade) [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 
 Tinycov is a small standalone command line utility written in python to plot the coverage of a BAM file quickly.
 This software was inspired by [Matt Edwards' genome coverage plotter](https://github.com/matted/genome_coverage_plotter).