gh-119961: Fix test workflow status badge in README (#119962)

Co-authored-by: Nikita Sobolev <[email protected]>

Author: wookie184

README.rst

@@ -1,7 +1,7 @@
 This is Python version 3.14.0 alpha 0
 =====================================
 
-.. image:: https://github.com/python/cpython/workflows/Tests/badge.svg
+.. image:: https://github.com/python/cpython/actions/workflows/build.yml/badge.svg?branch=main&event=push
    :alt: CPython build status on GitHub Actions
    :target: https://github.com/python/cpython/actions