chore: add custom sync repo settings (#757)

Author: parthea

.github/sync-repo-settings.yaml

@@ -0,0 +1,28 @@
+# https://github.com/googleapis/repo-automation-bots/tree/main/packages/sync-repo-settings
+# Rules for main branch protection
+branchProtectionRules:
+# Identifies the protection rule pattern. Name of the branch to be protected.
+# Defaults to `main`
+- pattern: main
+  requiresCodeOwnerReviews: true
+  requiresStrictStatusChecks: true
+  requiredStatusCheckContexts:
+    - 'cla/google'
+    - 'OwlBot Post Processor'
+    - 'system-tests (3.6)'
+    - 'system-tests (3.7)'
+    - 'system-tests (3.8)'
+    - 'system-tests (3.9)'
+    - 'system-tests'
+    - 'Kokoro'
+permissionRules:
+  - team: actools-python
+    permission: admin
+  - team: actools
+    permission: admin
+  - team: yoshi-python
+    permission: push
+  - team: python-samples-owners
+    permission: push
+  - team: python-samples-reviewers
+    permission: push