[CIR] GitHub workflows: move from macOS-13 to 15

Author: bcardosolopes

.github/workflows/clang-cir-tests.yml

@@ -36,4 +36,4 @@ jobs:
       build_target: check-clang-cir
       projects: clang;mlir
       extra_cmake_args: -DCLANG_ENABLE_CIR=ON
-      os_list: '["ubuntu-24.04", "windows-2022", "macOS-13"]'
+      os_list: '["ubuntu-24.04", "windows-2022", "macOS-15"]'