Replace Travis CI link with GitHub Actions badge and link

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WXd5SZvcgC73D24YWD3jK4

Author: claude

README.md

@@ -3,6 +3,7 @@ python-json-pointer
 
 [![PyPI version](https://img.shields.io/pypi/v/jsonpointer.svg)](https://pypi.python.org/pypi/jsonpointer/)
 [![Supported Python versions](https://img.shields.io/pypi/pyversions/jsonpointer.svg)](https://pypi.python.org/pypi/jsonpointer/)
+[![Tests](https://github.com/stefankoegl/python-json-pointer/actions/workflows/test.yaml/badge.svg?branch=master)](https://github.com/stefankoegl/python-json-pointer/actions/workflows/test.yaml)
 [![Coverage Status](https://coveralls.io/repos/github/stefankoegl/python-json-pointer/badge.svg?branch=master)](https://coveralls.io/github/stefankoegl/python-json-pointer?branch=master)
 
 
@@ -17,5 +18,5 @@ See source code for examples
 * Repository: https://github.com/stefankoegl/python-json-pointer.git
 * Documentation: https://python-json-pointer.readthedocs.org/
 * PyPI: https://pypi.python.org/pypi/jsonpointer
-* Travis CI: https://travis-ci.org/stefankoegl/python-json-pointer
+* GitHub Actions: https://github.com/stefankoegl/python-json-pointer/actions
 * Coveralls: https://coveralls.io/github/stefankoegl/python-json-pointer