Update README.rst

Author: pancetta

README.rst

@@ -80,7 +80,7 @@ This project also received funding from the `German Federal Ministry of Educatio
 The project also received help from the `Helmholtz Platform for Research Software Engineering - Preparatory Study (HiRSE_PS) <https://www.helmholtz-hirse.de/>`_.
 
 
-.. |badge-ga| image:: https://github.com/Parallel-in-Time/pySDC/actions/workflows/ci_pipeline.yml/badge.svg
+.. |badge-ga| image:: https://github.com/Parallel-in-Time/pySDC/actions/workflows/ci_pipeline.yml/badge.svg?branch=master
     :target: https://github.com/Parallel-in-Time/pySDC/actions/workflows/ci_pipeline.yml
 .. |badge-ossf| image:: https://bestpractices.coreinfrastructure.org/projects/6909/badge
     :target: https://bestpractices.coreinfrastructure.org/projects/6909