add lifecycle badge

Author: ablaom

README.md

@@ -4,7 +4,9 @@ Tool for testing implementations of the
 [LearnAPI.jl](https://juliaai.github.io/LearnAPI.jl/dev/) interface, for algorithms in
 machine learning and statistics
 
+[![Lifecycle:Maturing](https://img.shields.io/badge/Lifecycle-Maturing-007EC6)](https://github.com/JuliaAI/LearnAPI.jl/blob/dev/ROADMAP.md)
 [![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=
+9IWT9KYINZ)]
 
 See [LearnAPI.jl](https://juliaai.github.io/LearnAPI.jl/stable/) for documentation.