Update playground to require Go 1.20 to match SDK.

[lostluck]

The Go SDK will require go1.20 in v2.50, updating the various bits to ensure compatibility post release.

Should also allow the examples CI/CD task to pass in #27703 which updates the example code in a way that makes 1.20 required.

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[github-actions]

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[lostluck]

assign set of reviewers

[lostluck]

I don't understand the CI/CD failure. It's odd that it can't checkout the commit.

This does fix the go version error AFAICT however, as that was the previous CI/CD failure message.

[github-actions]

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R: @riteshghorse added as fallback since no labels match configuration

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[lostluck]

We don't have anyone who reviews Playground labels? Oh boy.

[riteshghorse]

LGTM!