Fix DIT test badge (#289)

Author: gdalle

DifferentiationInterfaceTest/README.md

@@ -1,6 +1,6 @@
 # DifferentiationInterfaceTest
 
-[![Build Status](https://github.com/gdalle/DifferentiationInterface.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/gdalle/DifferentiationInterface.jl/actions/workflows/CI.yml?query=branch%3Amain)
+[![Build Status](https://github.com/gdalle/DifferentiationInterface.jl/actions/workflows/Test.yml/badge.svg?branch=main)](https://github.com/gdalle/DifferentiationInterface.jl/actions/workflows/Test.yml?query=branch%3Amain)
 [![Coverage](https://codecov.io/gh/gdalle/DifferentiationInterface.jl/branch/main/graph/badge.svg)](https://app.codecov.io/gh/gdalle/DifferentiationInterface.jl)
 [![Code Style: Blue](https://img.shields.io/badge/code%20style-blue-4495d1.svg)](https://github.com/invenia/BlueStyle)
 [![DOI](https://zenodo.org/badge/740973714.svg)](https://zenodo.org/doi/10.5281/zenodo.11092033)