Specify code coverage as a static value.

Author: tim-schilling

README.rst

@@ -2,7 +2,7 @@
 Django Debug Toolbar |latest-version|
 =====================================
 
-|jazzband| |build-status| |docs| |python-support| |django-support|
+|jazzband| |build-status| |coverage| |docs| |python-support| |django-support|
 
 .. |latest-version| image:: https://img.shields.io/pypi/v/django-debug-toolbar.svg
    :target: https://pypi.python.org/pypi/django-debug-toolbar
@@ -16,6 +16,10 @@ Django Debug Toolbar |latest-version|
    :target: https://github.com/jazzband/django-debug-toolbar/actions
    :alt: Build Status
 
+.. |coverage| image:: https://img.shields.io/badge/Coverage-89%25-green
+   :target: https://github.com/jazzband/django-debug-toolbar/actions/workflows/test.yml?query=branch%3Amain
+   :alt: Test coverage status
+
 .. |docs| image:: https://img.shields.io/readthedocs/django-debug-toolbar/latest.svg
    :target: https://readthedocs.org/projects/django-debug-toolbar/
    :alt: Documentation status