Fix CI badge

Author: andreasnoack

README.md

@@ -1,7 +1,7 @@
 CategoricalArrays.jl
 ==================
 
-[![Build status](https://github.com/JuliaData/CategoricalArrays.jl/workflows/CI/badge.svg)](https://github.com/JuliaData/CategoricalArrays.jl/actions?query=workflow%3ACI+branch%3Amaster)
+[![CI](https://github.com/JuliaData/CategoricalArrays.jl/actions/workflows/ci.yml/badge.svg)](https://github.com/JuliaData/CategoricalArrays.jl/actions/workflows/ci.yml)
 [![Coveralls](https://coveralls.io/repos/github/JuliaData/CategoricalArrays.jl/badge.svg)](https://coveralls.io/github/JuliaData/CategoricalArrays.jl)
 [![Codecov](https://codecov.io/gh/JuliaData/CategoricalArrays.jl/branch/master/graph/badge.svg)](https://codecov.io/gh/JuliaData/CategoricalArrays.jl)