fix(arm64-osx-build): ensure llvm is installed to provide the correct…

… Clang version

We do not want to use Apple Clang and instead prefer latest.

pyproject.toml

@@ -37,7 +37,7 @@ LIBOGDF_INSTALL_PATH="$(pwd)/libOGDF"
 # For now build `x86_64` and `arm64` instead of `universal2` because we currently do
 # not build /usr/local/lib/libOGDF.dylib under `arm64` for some reason.
 archs = ["x86_64", "arm64"]
-before-all = ["brew install libomp"]
+before-all = ["brew install libomp llvm"]
 # NOTE: we delete build/ here as we're build multiple wheels and we support
 #       different SIMD commands on different platforms.
 before-build = """\