Add clang-16 for macos

Author: Bill-hbrhbr

.github/workflows/unit-tests.yaml

@@ -43,6 +43,12 @@ jobs:
         name: "Install coreutils (for md5sum)"
         run: "brew install coreutils"
 
+      - if: "matrix.os == 'macos-latest'"
+        name: "Install clang-16 (for c++20)"
+        run: |-
+          brew install llvm@16
+          ls -l $(brew --prefix llvm@16)/bin/clang
+
       - if: "matrix.os == 'ubuntu-20.04'"
         name: "Install gcc-10 (for c++20)"
         run: |-