Make clientTcpRtt optional

[WalshyDev]

$ curl -s --http1.1 https://reqinfo.walshy.dev | grep -E 'clientTcpRtt|httpProtocol'
        "clientTcpRtt": 16,
        "httpProtocol": "HTTP/1.1",
$ curl -s --http2 https://reqinfo.walshy.dev | grep -E 'clientTcpRtt|httpProtocol'
        "clientTcpRtt": 12,
        "httpProtocol": "HTTP/2",
$ curl -s --http3 https://reqinfo.walshy.dev | grep -E 'clientTcpRtt|httpProtocol'
        "httpProtocol": "HTTP/3",

HTTP/3 isn't over TCP so there's no TCP RTT sent.

[changeset-bot]

🦋 Changeset detected

Latest commit: 048ef7f

The changes in this PR will be included in the next version bump.

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Name	Type
@cloudflare/workers-types	Patch

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