ci: use macos-15-intel

[inkydragon]

The macOS-13 based runner images are being deprecated, consider switching to macOS-15 (macos-15-intel) or macOS 15 arm64 (macos-latest) instead. For more details see actions/runner-images#13046

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.17%. Comparing base (c733f17) to head (4c08755).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #203   +/-   ##
=======================================
  Coverage   97.17%   97.17%           
=======================================
  Files           8        8           
  Lines         813      813           
=======================================
  Hits          790      790           
  Misses         23       23           

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[Copilot]

Pull request overview

This PR updates the GitHub Actions CI configuration to migrate from the deprecated macos-13 runner to macos-15-intel in response to GitHub's deprecation notice. However, the changes inadvertently remove the pull_request: trigger, which would prevent CI from running on pull requests.

Key Changes:

• Updates the Intel macOS runner from macos-13 to macos-15-intel
• Critical Issue: Accidentally removes the pull_request: workflow trigger

---

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[Copilot]

The pull_request: trigger appears to have been inadvertently removed in this change. Based on the diff, this line is being deleted along with the workflow_dispatch line, but only workflow_dispatch is being re-added. This means the CI workflow will no longer run on pull requests, which is likely unintended and would significantly reduce CI coverage.

Please restore the pull_request: trigger to maintain CI execution on pull requests.

[inkydragon]

pull_request: The PR trigger condition is duplicated. This fixes the indentation issue for the manual trigger

Combinatorics.jl/.github/workflows/CI.yml

Lines 3 to 5 in c733f17

	on:
	pull_request:
	push: