Add macos-15 test runner #343

Job	Run time
CMake Build & Test (ubuntu-latest, Release, g++)	53s
CMake Build & Test (ubuntu-latest, Release, clang++)	54s
CMake Build & Test (ubuntu-latest, Debug, g++)	29s
CMake Build & Test (ubuntu-latest, Debug, clang++)	38s
CMake Build & Test (ubuntu-20.04, Release, g++)	53s
CMake Build & Test (ubuntu-20.04, Release, clang++)	1m 0s
CMake Build & Test (ubuntu-20.04, Debug, g++)	33s
CMake Build & Test (ubuntu-20.04, Debug, clang++)	40s
CMake Build & Test (windows-latest, Release, cl)	2m 23s
CMake Build & Test (windows-latest, Debug, cl)	1m 23s
CMake Build & Test (windows-2019, Release, cl)	1m 15s
CMake Build & Test (windows-2019, Debug, cl)	2m 16s
CMake Build & Test (macos-13, Release, g++)	1m 49s
CMake Build & Test (macos-13, Release, clang++)	1m 18s
CMake Build & Test (macos-13, Debug, g++)	1m 3s
CMake Build & Test (macos-13, Debug, clang++)	1m 0s
CMake Build & Test (macos-15, Release, g++)	35s
CMake Build & Test (macos-15, Release, clang++)	49s
CMake Build & Test (macos-15, Debug, g++)	26s
CMake Build & Test (macos-15, Debug, clang++)	27s
	20m 44s

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