feat: Add googleapis-auth as codeowner team

[lqiu96]

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Fixes #<issue_number_goes_here> ☕️

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[generated-files-bot]

Warning: This pull request is touching the following templated files:

• .github/sync-repo-settings.yaml

[blakeli0]

I think this change might be overridden to this file by the nightly owlbot template sync job, so we may need to add this file to the ignore list in owlbot.py. Is that correct @suztomo ?

[suztomo]

I just added Write role to googleapis-auth team via 'Settings'. Edit to .github/sync-repo-settings.yaml is not needed.

I observed OwlBot does not override the file googleapis/synthtool#1494 (comment)