Fix badge

README.rst

@@ -4,8 +4,8 @@ aiofiles: file support for asyncio
 .. image:: https://img.shields.io/pypi/v/aiofiles.svg
         :target: https://pypi.python.org/pypi/aiofiles
 
-.. image:: https://travis-ci.org/Tinche/aiofiles.svg?branch=master
-        :target: https://travis-ci.org/Tinche/aiofiles
+.. image:: https://github.com/Tinche/aiofiles/actions/workflows/main.yml/badge.svg
+        :target: https://github.com/Tinche/aiofiles/actions
 
 .. image:: https://codecov.io/gh/Tinche/aiofiles/branch/master/graph/badge.svg
         :target: https://codecov.io/gh/Tinche/aiofiles