Add download stats badge

Author: chezou

README.md

@@ -3,6 +3,7 @@
 [![Build Status](https://github.com/chezou/tabula-py/actions/workflows/pythontest.yml/badge.svg)](https://github.com/chezou/tabula-py/actions/workflows/pythontest.yml)
 [![PyPI version](https://badge.fury.io/py/tabula-py.svg)](https://badge.fury.io/py/tabula-py)
 [![Documentation Status](https://readthedocs.org/projects/tabula-py/badge/?version=latest)](https://tabula-py.readthedocs.io/en/latest/?badge=latest)
+![PyPI - Downloads](https://img.shields.io/pypi/dw/tabula-py)
 [![](https://img.shields.io/badge/-Sponsor-fafbfc?logo=GitHub%20Sponsors
 )](https://github.com/sponsors/chezou)