Github runner macos-12 -> macos-13.

Author: tzlaine

.github/workflows/macos-12.yml renamed to .github/workflows/macos-13.yml

@@ -1,4 +1,4 @@
-name: macos-12 - Clang 14
+name: macos-13 - Clang 14
 
 on:
   push:
@@ -16,7 +16,7 @@ jobs:
       matrix:
         cxx_std: [17]
 
-    runs-on: macos-12
+    runs-on: macos-13
 
     steps:
       - uses: actions/checkout@v4