Updated badge in README to include Python 3.6+ support.

Author: madpah

README.md

@@ -2,7 +2,7 @@
 
 [![CircleCI](https://circleci.com/gh/sonatype-nexus-community/cyclonedx-python-lib.svg?style=shield)](https://circleci.com/gh/sonatype-nexus-community/cyclonedx-python-lib)
 ![GitHub Workflow Status](https://img.shields.io/github/workflow/status/sonatype-nexus-community/cyclonedx-python-lib/Python%20CI)
-![Python Version Support](https://img.shields.io/badge/python-3.7%20%7C%203.8%20%7C%203.9-blue)
+![Python Version Support](https://img.shields.io/badge/python-3.6+-blue)
 [![GitHub license](https://img.shields.io/github/license/sonatype-nexus-community/cyclonedx-python-lib)](https://github.com/sonatype-nexus-community/cyclonedx-python-lib/blob/main/LICENSE)
 [![GitHub issues](https://img.shields.io/github/issues/sonatype-nexus-community/cyclonedx-python-lib)](https://github.com/sonatype-nexus-community/cyclonedx-python-lib/issues)
 [![GitHub forks](https://img.shields.io/github/forks/sonatype-nexus-community/cyclonedx-python-lib)](https://github.com/sonatype-nexus-community/cyclonedx-python-lib/network)