Update README.md

Author: taku910

README.md

@@ -3,6 +3,7 @@
 [![Build C++](https://github.com/google/sentencepiece/actions/workflows/cmake.yml/badge.svg)](https://github.com/google/sentencepiece/actions/workflows/cmake.yml)
 [![Build Wheels](https://github.com/google/sentencepiece/actions/workflows/wheel.yml/badge.svg)](https://github.com/google/sentencepiece/actions/workflows/wheel.yml)
 [![GitHub Issues](https://img.shields.io/github/issues/google/sentencepiece.svg)](https://github.com/google/sentencepiece/issues)
+![PyPI - Python Version](https://img.shields.io/pypi/pyversions/sentencepiece)
 [![PyPI version](https://badge.fury.io/py/sentencepiece.svg)](https://badge.fury.io/py/sentencepiece)
 [![PyPi downloads](https://img.shields.io/pypi/dm/sentencepiece?style=flat-square&logo=pypi&logoColor=white)](https://pypi.org/project/sentencepiece/)
 [![Contributions welcome](https://img.shields.io/badge/contributions-welcome-brightgreen.svg)](CONTRIBUTING.md)