fix(ci): set up LLVM and Clang

Author: tensorush

.github/workflows/ci.yaml

@@ -17,6 +17,11 @@ jobs:
       - name: Check out repository
         uses: actions/checkout@v4
 
+      - name: Set up LLVM and Clang
+        uses: KyleMayes/install-llvm-action@v2
+        with:
+          version: "18.1"
+
       - name: Set up Zig
         uses: mlugg/setup-zig@v1