Add macos-15 test runner

Author: serge1

.github/workflows/c-cpp.yml

@@ -15,7 +15,7 @@ jobs:
 
     strategy:
       matrix:
-        os: [ubuntu-latest, ubuntu-20.04, windows-latest, windows-2019, macos-13, macos-14]
+        os: [ubuntu-latest, ubuntu-20.04, windows-latest, windows-2019, macos-13, macos-15]
         build_type: [Release, Debug]
         cpp_compiler: [g++, clang++, cl]
         include:
@@ -43,10 +43,10 @@ jobs:
           - os: macos-13
             cpp_compiler: clang++
             c_compiler: clang
-          - os: macos-14
+          - os: macos-15
             cpp_compiler: g++
             c_compiler: gcc
-          - os: macos-14
+          - os: macos-15
             cpp_compiler: clang++
             c_compiler: clang
         exclude:
@@ -66,9 +66,9 @@ jobs:
             cpp_compiler: cl
           - os: macos-13
             cpp_compiler: cl
-          - os: macos-14
+          - os: macos-15
             cpp_compiler: cl
-          - os: macos-14
+          - os: macos-15
             cpp_compiler: cl
 
     steps: