Update badges

Author: devmotion

README.md

@@ -4,9 +4,9 @@
 
 [![Stable](https://img.shields.io/badge/docs-stable-blue.svg)](https://devmotion.github.io/POT.jl/stable)
 [![Dev](https://img.shields.io/badge/docs-dev-blue.svg)](https://devmotion.github.io/POT.jl/dev)
-[![Build Status](https://github.com/devmotion/POT.jl/workflows/CI/badge.svg)](https://github.com/devmotion/POT.jl/actions)
-[![Coverage](https://codecov.io/gh/devmotion/POT.jl/branch/master/graph/badge.svg)](https://codecov.io/gh/devmotion/POT.jl)
-[![Coverage](https://coveralls.io/repos/github/devmotion/POT.jl/badge.svg?branch=master)](https://coveralls.io/github/devmotion/POT.jl?branch=master)
+[![Build Status](https://github.com/devmotion/POT.jl/workflows/CI/badge.svg?branch=main)](https://github.com/devmotion/POT.jl/actions?query=workflow%3ACI+branch%3Amain)
+[![Coverage](https://codecov.io/gh/devmotion/POT.jl/branch/main/graph/badge.svg)](https://codecov.io/gh/devmotion/POT.jl)
+[![Coverage](https://coveralls.io/repos/github/devmotion/POT.jl/badge.svg?branch=main)](https://coveralls.io/github/devmotion/POT.jl?branch=main)
 [![Code Style: Blue](https://img.shields.io/badge/code%20style-blue-4495d1.svg)](https://github.com/invenia/BlueStyle)
 
 This package was originally part of [OptimalTransport.jl](https://github.com/zsteve/OptimalTransport.jl).