Update README.md

Author: ourownstory

README.md

@@ -1,6 +1,6 @@
 [![GitHub release (latest SemVer)](https://img.shields.io/github/v/release/ourownstory/neural_prophet?logo=github)](https://github.com/ourownstory/neural_prophet/releases)
 [![Pypi_Version](https://img.shields.io/pypi/v/neuralprophet.svg)](https://pypi.python.org/pypi/neuralprophet)
-[![Python Version](https://img.shields.io/badge/python-3.7+-blue?logo=python)](https://www.python.org/)
+[![Python Version](https://img.shields.io/badge/python-3.9+-blue?logo=python)](https://www.python.org/)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![License](https://img.shields.io/badge/license-MIT-brightgreen)](https://opensource.org/licenses/MIT)
 [![Tests](https://github.com/ourownstory/neural_prophet/actions/workflows/ci.yml/badge.svg)](https://github.com/ourownstory/neural_prophet/actions/workflows/ci.yml)