Restore to latest LLVM

Author: xxuejie

.github/workflows/rust.yml

@@ -43,7 +43,7 @@ jobs:
       with:
         submodules: true
     - name: Install latest llvm & lld
-      run: brew install llvm@20 lld
+      run: brew install llvm lld
     - uses: actions-rust-lang/setup-rust-toolchain@v1
     - name: Prepare, build, test, clippy, format
       run: make prepare build test clippy fmt