chore: make samples 3.6 check optional (#669)

Co-authored-by: Anthonios Partheniou <[email protected]>

Author: busunkim96

.github/sync-repo-settings.yaml

@@ -11,6 +11,5 @@ branchProtectionRules:
     - 'Kokoro system-3.8'
     - 'cla/google'
     - 'Samples - Lint'
-    - 'Samples - Python 3.6'
     - 'Samples - Python 3.7'
     - 'Samples - Python 3.8'