Publish main to github nuget

[VladislavAntonyuk]

Description of Change

Linked Issues

• Fixes #

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

[Copilot]

Pull Request Overview

This PR updates the GitHub Actions workflow for publishing to NuGet by modifying the signing conditions and splitting the release process into separate jobs.

• Updated the sign job condition to include non-pull_request events.
• Introduced a new release-main job for branch pushes (non-PR, non-tag events) to publish signed packages.
• Retained the existing release-nuget job for tag-based releases.

[bijington]

Thanks @VladislavAntonyuk how do we go about testing this? Is it a case of merging and then seeing what happens?

[VladislavAntonyuk]

Thanks @VladislavAntonyuk how do we go about testing this? Is it a case of merging and then seeing what happens?

Yes, as it is only configured to the main branch and tags