set TLS 1.3 as default for webhooks

[sozercan]

Describe the solution you'd like
[A clear and concise description of what you want to happen.]
As discussed in #1424, TLS 1.3 should be default in next version

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Gatekeeper version:
• Kubernetes version: (use kubectl version):