Pin .NET SDK to 9.0.313 via global.json

[Copilot]

The repo had no SDK version pin, leaving builds subject to whatever SDK version happened to be installed. This adds a global.json at the repo root to consistently enforce .NET SDK 9.0.313 across local dev and CI.

Changes

• global.json (new): pins SDK to 9.0.313

{
  "sdk": {
    "version": "9.0.313"
  }
}

Existing target frameworks (net8.0-windows) are unaffected; the .NET 9 SDK builds net8.0 targets without changes.

Original prompt

Upgrade the .NET SDK used by the microsoft/winget-create repository to version 9.0.313.

Please make the necessary code and configuration changes in the repository so that builds and CI use .NET SDK 9.0.313 consistently. Investigate common locations such as global.json, GitHub Actions workflow setup steps, documentation, and any build/test configuration files that pin or reference the SDK version.

Requirements:

• Update all relevant version pins/references to .NET SDK 9.0.313.
• Keep the change minimal and focused on the SDK upgrade.
• Verify whether CI/workflows require any corresponding updates.
• Create a pull request with a concise summary of the changes made.

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: Create a PR upgrading .NET SDK to 9.0.313

Assistant: I’m waiting for your response to the confirmation dialog so I can continue creating the PR.

This pull request was created from Copilot chat.

[AmelBawa-msft]

/azp run

[azure-pipelines]

Azure Pipelines could not run because the pipeline triggers exclude this branch/path.