Update badges in README.rst (#426)

README.rst

@@ -1,14 +1,11 @@
 async-timeout
 =============
-.. image:: https://travis-ci.com/aio-libs/async-timeout.svg?branch=master
-    :target: https://travis-ci.com/aio-libs/async-timeout
+.. image:: https://github.com/aio-libs/async-timeout/actions/workflows/ci.yml/badge.svg
+    :target: https://github.com/aio-libs/async-timeout/actions/workflows/ci.yml
 .. image:: https://codecov.io/gh/aio-libs/async-timeout/branch/master/graph/badge.svg
     :target: https://codecov.io/gh/aio-libs/async-timeout
 .. image:: https://img.shields.io/pypi/v/async-timeout.svg
     :target: https://pypi.python.org/pypi/async-timeout
-.. image:: https://badges.gitter.im/Join%20Chat.svg
-    :target: https://gitter.im/aio-libs/Lobby
-    :alt: Chat on Gitter
 
 asyncio-compatible timeout context manager.