Update LLVM version in MacOS workflow (18)

Author: howetuft

.github/workflows/wheel-builder.yml

@@ -196,7 +196,7 @@ jobs:
         if: runner.os == 'macOS'
         shell: bash
         run: |
-            _T=$(brew --prefix llvm@15)
+            _T=$(brew --prefix llvm@18)
             echo "CXX=${_T}/bin/clang++" >> $GITHUB_ENV
             echo "CC=${_T}/bin/clang" >> $GITHUB_ENV
             #echo "AR=${_T}/bin/ar" >> $GITHUB_ENV