Use LLVM-18 for macOS ARM

.github/workflows/ci.yml

@@ -99,8 +99,8 @@ jobs:
       - name: Download LLVM (MacOS ARM)
         if: matrix.os == 'macos-14'
         run: |
-          brew install llvm@20 wasmtime [email protected]
-          echo "/opt/homebrew/opt/llvm@20/bin" >> $GITHUB_PATH
+          brew install llvm@18 wasmtime [email protected]
+          echo "/opt/homebrew/opt/llvm@18/bin" >> $GITHUB_PATH
 
       - name: Build Odin
         run: ./build_odin.sh release