Add proper codecov badge

Author: pauljuerss

README.md

@@ -8,7 +8,8 @@
 ![Lifecycle](https://img.shields.io/badge/lifecycle-archived-red.svg)
 ![Lifecycle](https://img.shields.io/badge/lifecycle-dormant-blue.svg) -->
 [![Build status](https://github.com/JuliaImageRecon/TrainingPhantoms.jl/workflows/CI/badge.svg)](https://github.com/JuliaImageRecon/TrainingPhantoms.jl/actions)
-[![codecov.io](http://codecov.io/github/JuliaImageRecon/TrainingPhantoms.jl/coverage.svg?branch=master)](http://codecov.io/github/JuliaImageRecon/TrainingPhantoms.jl?branch=master)
+[![codecov][codecov-img]][codecov-url]
+<!--[![codecov.io](http://codecov.io/github/JuliaImageRecon/TrainingPhantoms.jl/coverage.svg?branch=master)](http://codecov.io/github/JuliaImageRecon/TrainingPhantoms.jl?branch=master) -->
 
 ## Purpose
 This Julia package contains a collection of methods that generate different kinds of phantom with the aim of being used to synthesise machine learning datasets. Currently, there exist two generator methods
@@ -26,3 +27,7 @@ To help you get started, we have provided examples for each generator. The can b
 <!--- ![ellipsoidPhantom2](https://github.com/JuliaImageRecon/TrainingPhantoms.jl/assets/115639115/863b0769-9643-4858-9201-3f94311ab2ba)
 ![vesselPhantom](https://github.com/JuliaImageRecon/TrainingPhantoms.jl/assets/115639115/79c95f1f-b284-4562-8464-9b12ac3edf7d) --->
 ![combined](https://github.com/JuliaImageRecon/TrainingPhantoms.jl/assets/115639115/5babfffa-c464-4b32-99b4-da8cd4e12e86)
+
+
+[codecov-img]: https://codecov.io/github/JuliaImageRecon/TrainingPhantoms.jl/coverage.svg?branch=main
+[codecov-url]: https://codecov.io/github/JuliaImageRecon/TrainingPhantoms.jl?branch=main