README: Update badges

Author: nnicandro

README.org

@@ -2,9 +2,8 @@ An interface to communicate with Jupyter kernels in Emacs.
 
 #+BEGIN_HTML
 <a href="https://melpa.org/#/jupyter"><img src="https://melpa.org/packages/jupyter-badge.svg"></a>
-<a href="https://travis-ci.com/dzop/emacs-jupyter"><img src="https://travis-ci.com/dzop/emacs-jupyter.svg?branch=master"></a>
-<a href="https://ci.appveyor.com/project/dzop/emacs-jupyter/branch/master"><img src="https://ci.appveyor.com/api/projects/status/htj8e742k604w2vk/branch/master?svg=true"></a>
-<a href="https://gitter.im/emacs-jupyter/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge"><img src="https://badges.gitter.im/emacs-jupyter/community.svg"></a>
+<a href="https://github.com/emacs-jupyter/jupyter/actions/workflows/test.yml"><img src="https://github.com/emacs-jupyter/jupyter/actions/workflows/test.yml/badge.svg" /></a>
+<a href="https://gitter.im/emacs-jupyter/community?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge"><img src="https://badges.gitter.im/emacs-jupyter/community.svg" /></a>
 #+END_HTML
 
 * Table of Contents                                                     :TOC: