Maintenance: GitHub Action Runners for NWS Swift

[roblabs]

I did some maintenance on the GitHub Actions, with mixed results. No PR anticipated, as I have a few PRs already pending and I care about those first.

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Commits on my fork in the branch actions/runner in case someone wants to get this working:

• Update uses actions and Xcode versions
• GitHub Actions: Update uses actions and Xcode versions for Apple & Linux workflows

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• The actions dependencies were updated to latest: setup-xcode, checkout, and cache
• https://github.com/roblabs/NationalWeatherService-Swift/actions/runs/10516809517/job/29139743036
• The workflow called Apple still runs on macos-latest, with Xcode 15.4.0,
  • but only the macos job is successful
  • The ios job fails
  • The workflow Linux doesn't work for either of the two jobs