chore(python): Add kokoro configs for python 3.10 samples testing (#147)

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scheduler/snippets/noxfile.py

@@ -87,7 +87,7 @@ def get_pytest_env_vars() -> Dict[str, str]:
 
 # DO NOT EDIT - automatically generated.
 # All versions used to test samples.
-ALL_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
+ALL_VERSIONS = ["3.6", "3.7", "3.8", "3.9", "3.10"]
 
 # Any default versions that should be ignored.
 IGNORED_VERSIONS = TEST_CONFIG["ignored_versions"]