fix: update shiled source for build status

Author: Agus Makmun

README.md

@@ -364,8 +364,8 @@ Checkout at http://127.0.0.1:8000/simple-form/ on your browser.
 [9]: https://img.shields.io/badge/Django-3.2%20%3E=%204.1-green.svg
 [10]: https://www.djangoproject.com
 
-[11]: https://travis-ci.org/agusmakmun/django-markdown-editor.svg?branch=master
-[12]: https://travis-ci.org/agusmakmun/django-markdown-editor
+[11]: https://img.shields.io/github/workflow/status/agusmakmun/django-markdown-editor/Run%20tests
+[12]: https://github.com/agusmakmun/django-markdown-editor/actions/workflows/run-tests.yml
 
 [13]: https://github.com/agusmakmun/django-markdown-editor/wiki
 [14]: https://github.com/agusmakmun/django-markdown-editor/tree/master/martor_demo/app/templates