Update README badges for GitHub Actions and Codecov

Replace outdated Coveralls badge with Codecov, add GitHub Actions
workflow status badges for tests and build, and add PyPI version
and license badges.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: wmayner

README.md

@@ -4,9 +4,13 @@
   </a>
 </p>
 
-[![Documentation badge](https://readthedocs.org/projects/pyphi/badge/?style=flat-square&maxAge=600)](https://pyphi.readthedocs.io/)
-[![Coveralls.io badge](https://img.shields.io/coveralls/wmayner/pyphi/develop.svg?style=flat-square&maxAge=600)](https://coveralls.io/github/wmayner/pyphi?branch=develop)
-[![Python versions badge](https://img.shields.io/pypi/pyversions/pyphi.svg?style=flat-square&maxAge=86400)](https://wiki.python.org/moin/Python2orPython3)
+[![Tests](https://img.shields.io/github/actions/workflow/status/wmayner/pyphi/test.yml?branch=develop&style=flat-square&label=tests)](https://github.com/wmayner/pyphi/actions/workflows/test.yml)
+[![Build](https://img.shields.io/github/actions/workflow/status/wmayner/pyphi/build.yml?branch=develop&style=flat-square&label=build)](https://github.com/wmayner/pyphi/actions/workflows/build.yml)
+[![Codecov](https://img.shields.io/codecov/c/github/wmayner/pyphi/develop?style=flat-square)](https://codecov.io/gh/wmayner/pyphi)
+[![Documentation](https://img.shields.io/readthedocs/pyphi/stable?style=flat-square)](https://pyphi.readthedocs.io/)
+[![PyPI version](https://img.shields.io/pypi/v/pyphi?style=flat-square)](https://pypi.org/project/pyphi/)
+[![Python 3.12+](https://img.shields.io/pypi/pyversions/pyphi?style=flat-square)](https://pypi.org/project/pyphi/)
+[![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg?style=flat-square)](https://www.gnu.org/licenses/gpl-3.0)
 
 PyPhi is a Python library for computing integrated information (𝚽), and the
 associated quantities and objects.