Fix missing checkout for Slither CI job

Author: ermyas

.github/workflows/ci.yml

@@ -32,6 +32,11 @@ jobs:
       contents: read
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          persist-credentials: false
+          submodules: recursive
+
       - uses: crytic/slither-action@b52cc1cbfee9ca3e8722dd5224299d16c9a6b80f # v0.4.2
         with:
           fail-on: high