Readme: fix test status badges

GitHub has changed the workflow badge urls again
(and doesn't redirect the old ones).

Author: medmunds

README.rst

@@ -66,11 +66,11 @@ The package is released under the BSD license.
 
 .. END shared-intro
 
-.. image:: https://github.com/anymail/django-anymail/workflows/test/badge.svg?branch=main
+.. image:: https://github.com/anymail/django-anymail/actions/workflows/test.yml/badge.svg?branch=main
        :target: https://github.com/anymail/django-anymail/actions?query=workflow:test+branch:main
        :alt:    test status in GitHub Actions
 
-.. image:: https://github.com/anymail/django-anymail/workflows/integration-test/badge.svg?branch=main
+.. image:: https://github.com/anymail/django-anymail/actions/workflows/integration-test.yml/badge.svg?branch=main
        :target: https://github.com/anymail/django-anymail/actions?query=workflow:integration-test+branch:main
        :alt:    integration test status in GitHub Actions