doc: link badge to pypi in readme (#94)

Co-authored-by: anna-singleton-resolver <anna.singleton@resolver.com>

Author: anna-singleton-resolver

README.md

@@ -1,5 +1,7 @@
 # Athena Client Library
 
+![PyPI - Version](https://img.shields.io/pypi/v/resolver-athena-client)
+
 This is a Python library for interacting with the Athena API (Resolver Unknown
 CSAM Detection).