Update build_llvm.yml

Author: makslevental

.github/workflows/build_llvm.yml

@@ -121,7 +121,7 @@ jobs:
           submodules: true
 
       - name: "Setup base"
-        if: matrix.runs-on != "self-hosted-macos-arm64"
+        if: (matrix.runs-on != "self-hosted-macos-arm64")
         uses: ./.github/actions/setup_base
         id: setup_base
         with: