Fix PyPI badge URL to point to correct project

Author: gabino

README.md

@@ -2,7 +2,7 @@
 
 [![test](https://github.com/cuenca-mx/cep-python/workflows/test/badge.svg)](https://github.com/cuenca-mx/cep-python/actions?query=workflow%3Atest)
 [![codecov](https://codecov.io/gh/cuenca-mx/cep-python/branch/master/graph/badge.svg)](https://codecov.io/gh/cuenca-mx/cep-python)
-[![PyPI](https://img.shields.io/pypi/v/cuenca.svg)](https://pypi.org/project/cepmex/)
+[![PyPI](https://img.shields.io/pypi/v/cepmex.svg)](https://pypi.org/project/cepmex/)
 
 Python client library for CEP (http://www.banxico.org.mx/cep/)