chore: require CODEOWNER review and up to date branches (#356)

These two lines bring the rules on this repo in line with the defaults: https://github.com/googleapis/repo-automation-bots/blob/63c858e539e1f4d9bb8ea66e12f9c0a0de5fef55/packages/sync-repo-settings/src/required-checks.json#L40-L50

Author: busunkim96

.github/sync-repo-settings.yaml

@@ -4,10 +4,12 @@ branchProtectionRules:
 # Identifies the protection rule pattern. Name of the branch to be protected.
 # Defaults to `master`
 - pattern: master
+ requiresCodeOwnerReviews: true
+ requiresStrictStatusChecks: true
  requiredStatusCheckContexts:
  - 'Kokoro'
  - 'cla/google'
  - 'Samples - Lint'
  - 'Samples - Python 3.6'
  - 'Samples - Python 3.7'
- - 'Samples - Python 3.8' 
+ - 'Samples - Python 3.8'