feat: add ruleset option do_not_enforce_on_create

[MattMencel]

Optional attribute added to rules.required_status_checks.

Depends on google/go-github#3245. Possibly in the next release > v64.0.0. Placing the PR in Draft mode until the release is available.

Resolves #2360

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Before the change?

• The option to allow repositories and branches to be created if a check would otherwise prohibit it, was not available.

After the change?

• The option to allow repositories and branches to be created if a check would otherwise prohibit it, is available through the provider.

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

• Yes
• No

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