👷 use Clang compiler

.github/workflows/windows_clang.yml

@@ -12,7 +12,7 @@ jobs:
       - name: install Clang
         run: choco install -y llvm
       - name: cmake
-        run: cmake -S . -B build -D CMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
+        run: cmake -S . -B build -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_BUILD_TYPE=Debug -DJSON_BuildTests=On
       - name: build
         run: cmake --build build --parallel 10
       - name: test