Change installer URLs in LINQPad manifest

[albahari]

Updated installer URLs to new CDN, prior to Azure Front Door phaseout.

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  • Resolves #[Issue Number]

Manifests

• Have you checked that there aren't other open pull requests for the same manifest update/change?
• This PR only modifies one (1) manifest
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• Have you tested your manifest locally with winget install --manifest <path>?
• Does your manifest conform to the 1.10 schema?

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Validation Pipeline Run WinGetSvc-Validation-132-338795-20260212-1

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