update codecov badge

Author: ablaom

README.md

@@ -5,6 +5,6 @@ Tool for testing implementations of the
 machine learning and statistics
 
 [![Build Status](https://github.com/JuliaAI/LearnTestAPI.jl/workflows/CI/badge.svg)](https://github.com/JuliaAI/LearnTestAPI.jl/actions)
-[![codecov](https://codecov.io/gh/JuliaAI/LearnTestAPI.jl/graph/badge.svg?token=9IWT9KYINZ)]
+[![codecov](https://codecov.io/gh/JuliaAI/LearnTestAPI.jl/graph/badge.svg?token=gCIQfDtzMt)](https://codecov.io/gh/JuliaAI/LearnTestAPI.jl)
 
 See [LearnAPI.jl](https://juliaai.github.io/LearnAPI.jl/stable/) for documentation.