Upgrade to MacOS 15

MacOS 13 has been deprecated. See
https://github.blog/changelog/2025-09-19-github-actions-macos-13-runner-image-is-closing-down/

Author: AlexanderWells-diamond

.github/workflows/code.yml

@@ -53,13 +53,13 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, windows-latest, macos-13]
+        os: [ubuntu-latest, windows-latest, macos-15-intel]
         python: [cp37, cp38, cp39, cp310, cp311, cp312]
 
 
         include:
           # Put coverage and results files in the project directory for mac
-          - os: macos-13
+          - os: macos-15-intel
             cov_file: "{project}/dist/coverage.xml"
             results_file: "{project}/dist/pytest-results.xml"
           # And for windows