DOC: Fix CI badge

to accurately reflect actual CI status on main [ci skip]

Author: pllim

README.rst

@@ -63,7 +63,7 @@ License
 Astropy is licensed under a 3-clause BSD style license - see the
 `LICENSE.rst <LICENSE.rst>`_ file.
 
-.. |Actions Status| image:: https://github.com/astropy/astropy/workflows/CI/badge.svg
+.. |Actions Status| image:: https://github.com/astropy/astropy/actions/workflows/ci_workflows.yml/badge.svg
     :target: https://github.com/astropy/astropy/actions
     :alt: Astropy's GitHub Actions CI Status