Update macOS runner from deprecated macos-13 to macos-latest

[Copilot]

The exercises workflow was using macos-13, which was deprecated in December 2025 and is no longer available, causing the macOS job to be immediately cancelled.

Changes

• Updated .github/workflows/exercises.yml to use macos-latest (currently macOS-15 Arm64) instead of macos-13

# Before
runs-on: ${{ matrix.os == 'linux' && 'ubuntu-24.04' || (matrix.os == 'macOS' && 'macos-13' || 'windows-2022') }}

# After
runs-on: ${{ matrix.os == 'linux' && 'ubuntu-24.04' || (matrix.os == 'macOS' && 'macos-latest' || 'windows-2022') }}

Using macos-latest ensures automatic tracking of the latest stable macOS runner as GitHub updates their infrastructure.

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• github.blog
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)
• https://api.github.com/repos/exercism/nim/actions/jobs/62430984198
  • Triggering command: /usr/bin/curl curl -s -H Accept: application/vnd.github+json REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)