release 1.20.0

[SaitejaTamma]

What type of PR is this?

Uncomment only one /kind <> line, press enter to put that in a new line, and remove leading whitespace from that line:

/kind breaking
/kind bug
/kind cleanup
/kind documentation
/kind feature
/kind hotfix

/kind release

What this PR does / Why we need it:

Which issue(s) this PR fixes:

Work on #2430

Special notes for your reviewer:

[agones-bot]

Build Succeeded 👏

Build Id: 6bb10abb-673b-45bb-b12b-f39d3c2e3a94

The following development artifacts have been built, and will exist for the next 30 days:

• image: gcr.io/agones-images/agones-controller:1.20.0-96ff251
• image: gcr.io/agones-images/agones-ping:1.20.0-96ff251
• Linux C++ SDK (build): agonessdk-1.20.0-96ff251-linux-arch_64.tar.gz
• SDK Server: agonessdk-server-1.20.0-96ff251.zip

A preview of the website (the last 30 builds are retained):

• https://96ff251-dot-preview-dot-agones-images.appspot.com/

To install this version:

• git fetch https://github.com/googleforgames/agones.git pull/2431/head:pr_2431 && git checkout pr_2431
• helm install ./install/helm/agones --namespace agones-system --name agones --set agones.image.tag=1.20.0-96ff251

[markmandel]

Looks great! Merge when ready!

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: markmandel, roberthbailey, SaitejaTamma, steven-supersolid

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The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [markmandel,roberthbailey]

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