README.md: fix coverage badge, because default branch is master and not main

README.md

@@ -3,7 +3,7 @@
 [![PyPI - Version](https://img.shields.io/pypi/v/orekit-jpype.svg)](https://pypi.org/project/orekit-jpype)
 [![PyPI - Python Version](https://img.shields.io/pypi/pyversions/orekit-jpype.svg)](https://pypi.org/project/orekit-jpype)
 [![Pipeline passing](https://gitlab.orekit.org/orekit/orekit_jpype/badges/master/pipeline.svg?ignore_skipped=true)](https://gitlab.orekit.org/orekit/orekit_jpype/-/pipelines)
-[![coverage](https://gitlab.orekit.org/orekit/orekit_jpype/badges/main/coverage.svg)](https://gitlab.orekit.org/orekit/orekit_jpype/-/graphs/master/charts)
+[![coverage report](https://gitlab.orekit.org/orekit/orekit_jpype/badges/master/coverage.svg)](https://gitlab.orekit.org/orekit/orekit_jpype/-/commits/master)
 
 An alternative implementation of orekit python wrapper based on Jpype and stubs generated by stubgenj. The interface is largely similar to the original JCC wrapped orekit version which is a more capable wrapper as it can subclass java classes, which Jpype cannot. The Jpype version is however easy to install, use and for most purposes sufficient.