Update macOS runners from macos-13 to macos-15-intel

[Copilot]

Motivation

GitHub Actions deprecated the macos-13 runner. Per runner-images#13046, the x86_64 replacement is macos-15 macos-15-intel.

How to test the behavior?

Push to a branch and verify that the macOS Python 3.9 minimum test jobs run on macos-15 runners without deprecation warnings.

Checklist

• Did you update CHANGELOG.md with your changes?
• Does the PR clearly describe the problem and the solution?
• Have you reviewed our Contributing Guide?
• Does the PR use "Fix #XXX" notation to tell GitHub to close the relevant issue numbered XXX when the PR is merged?

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Bug]: Use macos-15 runner for x86_64 based minimum testing</issue_title>
<issue_description>### What happened?

From https://github.com/hdmf-dev/hdmf/actions/runs/20056027655/job/57522568845?pr=1352

The macOS-13 based runner images are now retired. For more details, see https://github.com/actions/runner-images/issues/13046.
--
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 https://github.com/actions/runner-images/issues/13046

Steps to Reproduce

Run the "Run tests" workflow

Traceback

Operating System

macOS

Python Version

3.9

Package Versions

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes [Bug]: Use macos-15 runner for x86_64 based minimum testing #1353

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.44%. Comparing base (cec7126) to head (492150f).
⚠️ Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev    #1363   +/-   ##
=======================================
  Coverage   92.44%   92.44%           
=======================================
  Files          42       42           
  Lines        9747     9747           
  Branches     1979     1979           
=======================================
  Hits         9011     9011           
  Misses        462      462           
  Partials      274      274           

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