Migrate to macos-15 for x86_64

Author: dcamron

.github/workflows/packages.yml

@@ -22,7 +22,7 @@ jobs:
           - ["Linux-arm64", "ubuntu-24.04-arm"]
           - ["Windows-x64", "windows-latest"]
           - ["Windows-arm64", "windows-11-arm"]
-          - ["macOS-x64", "macos-13"]  # Final macOS Intel platform
+          - ["macOS-x64", "macos-15-intel"]
           - ["macOS-arm64", "macos-latest"]
 #        python-version:
 #          - [ "CPython 3.10", "cp310" ]