CI (verilator): Checkout submodules with GH action

Configure the `actions/checkout` to fetch submodules recursively instead
of adding a separate step doing the same manually.

.github/workflows/verilator_compatibility.yml

@@ -18,8 +18,8 @@ jobs:
       - name: trigger reason
         run: echo "Trigger Reason:" ${{ github.event.inputs.reason }}
       - uses: actions/checkout@v4
-      - name: checkout submodules
-        run: git submodule update --init --recursive
+        with:
+          submodules: 'recursive'
       - name: install apt packages
         run: sudo apt-get update && sudo apt-get -y install git make autoconf g++ flex bison libfl2 libfl-dev
       - name: compile verilator