Switch CI from macos-13 to macos-15-intel

Author: mhsmith

.github/workflows/ci.yml

@@ -170,7 +170,7 @@ jobs:
           - os: linux
             runs-on: ubuntu-22.04
           - os: macos
-            runs-on: macos-13
+            runs-on: macos-15-intel
           - os: windows
             runs-on: windows-2022