🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Author: gcf-owl-bot[bot]

CONTRIBUTING.rst

@@ -22,7 +22,7 @@ In order to add a feature:
   documentation.
 
 - The feature must work fully on the following CPython versions:
-  3.6, 3.7, 3.8, 3.9, 3.10 and 3.11 on both UNIX and Windows.
+  3.7, 3.8, 3.9, 3.10 and 3.11 on both UNIX and Windows.
 
 - The feature must not add unnecessary dependencies (where
   "unnecessary" is of course subjective, but new dependencies should
@@ -221,14 +221,12 @@ Supported Python Versions
 
 We support:
 
--  `Python 3.6`_
 -  `Python 3.7`_
 -  `Python 3.8`_
 -  `Python 3.9`_
 -  `Python 3.10`_
 -  `Python 3.11`_
 
-.. _Python 3.6: https://docs.python.org/3.6/
 .. _Python 3.7: https://docs.python.org/3.7/
 .. _Python 3.8: https://docs.python.org/3.8/
 .. _Python 3.9: https://docs.python.org/3.9/
@@ -241,7 +239,7 @@ Supported versions can be found in our ``noxfile.py`` `config`_.
 .. _config: https://github.com/googleapis/google-auth-library-python-oauthlib/blob/main/noxfile.py
 
 
-We also explicitly decided to support Python 3 beginning with version 3.6.
+We also explicitly decided to support Python 3 beginning with version 3.7.
 Reasons for this include:
 
 -  Encouraging use of newest versions of Python 3