Remove version constraint

There are currently already uses on 3.11 despite how it would not have been supported until now. We do not want to arbitrarily cut off access to 3.12 pioneers. We already publish in the documentation that up to 3.11 is supported.

setup.py

@@ -15,5 +15,5 @@
         install_requires=['requests', 'urllib3', 'deprecation'],
         author='PagerDuty',
         author_email='support@pagerduty.com',
-        python_requires='>=3.6, <3.12'
+        python_requires='>=3.6'
     )