Update CI badge; remove old config

Author: kislyuk

.travis.yml

@@ -178,8 +178,8 @@ License
 -------
 Licensed under the terms of the `Apache License, Version 2.0 <http://www.apache.org/licenses/LICENSE-2.0>`_.
 
-.. image:: https://img.shields.io/travis/XML-Security/signxml.svg
-        :target: https://travis-ci.org/XML-Security/signxml
+.. image:: https://github.com/XML-Security/signxml/workflows/Test%20suite/badge.svg
+        :target: https://github.com/XML-Security/signxml/actions
 .. image:: https://codecov.io/github/XML-Security/signxml/coverage.svg?branch=master
         :target: https://codecov.io/github/XML-Security/signxml?branch=master
 .. image:: https://img.shields.io/pypi/v/signxml.svg