Test against latest LLVM on mac

Author: xxuejie

.github/workflows/rust.yml

@@ -31,8 +31,8 @@ jobs:
     - uses: actions/checkout@v4
       with:
         submodules: true
-    - name: Install llvm 18
-      run: brew install llvm@18
+    - name: Install latest llvm
+      run: brew install llvm
     - uses: actions-rust-lang/setup-rust-toolchain@v1
     - name: Prepare, build, test, clippy, format
       run: make prepare build test clippy fmt