docs: show that Python 3.9 and 3.10 are supported in classifiers (#351)

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Fixes #342 🦕

Author: tswast

.github/sync-repo-settings.yaml

@@ -13,3 +13,5 @@ branchProtectionRules:
     - 'Samples - Python 3.6'
     - 'Samples - Python 3.7'
     - 'Samples - Python 3.8'
+    - 'Samples - Python 3.9'
+    - 'Samples - Python 3.10'

setup.py

@@ -72,6 +72,8 @@
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Operating System :: OS Independent",
         "Topic :: Internet",
     ],