Don't forget to install clang-cl

.github/workflows/build_cibuildwheel.yml

@@ -21,6 +21,10 @@ jobs:
       - name: Install cibuildwheel
         run: python -m pip install cibuildwheel==2.3.1
 
+      - name: Install LLVM (clang-cl) on windows
+        run: choco install -y llvm
+        if: runner.os == 'Windows'
+
       - name: Build wheels
         run: python -m cibuildwheel --output-dir wheelhouse
         # to supply options, put them in 'env', like: