Add raywainman as reviewer of VPA

[raywainman]

I have met all requirements to join as reviewer:

• Member since early May
• 21 PRs authored and closed - though many of them are fairly trivial release-related PRs.
• 19 PRs reviewed and closed
• Familiar with codebase as I interact with it on a daily basis.
• Also active on Slack answering questions and in SIG meetings.

[kwiesmueller]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: kwiesmueller, raywainman

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• vertical-pod-autoscaler/OWNERS [kwiesmueller]

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