set correct commit hash for llvm clone

Author: jorendumoulin

.github/workflows/build-mlir.yml

@@ -27,7 +27,7 @@ jobs:
       run: |
         git clone https://github.com/llvm/llvm-project.git
         cd llvm-project
-        git checkout 98e674c9f16d677d95c67bc130e267fae331e43c
+        git checkout d401987fe349a87c53fe25829215b080b70c0c1a
         cd ..
 
     - name: Install dependencies