ci: Correct usage of list-make-prerequisites action

.github/workflows/ci.yml

@@ -94,13 +94,13 @@ jobs:
       - uses: actions/checkout@v2
         with:
           submodules: 'recursive'
-      - name: Get Verilator prerequisites hash
+      - name: Hash Verilator prerequisites
         id: verilator-hash
         uses: colluca/list-make-prerequisites@v1
         with:
           working-directory: target/snitch_cluster
           target: bin/snitch_cluster.vlt
-          recursive: true
+          flags: --recursive
       - name: Set up cache for Verilator build
         id: verilator-cache
         uses: actions/cache@v3