Revert "Disable Foundry for slither-action" (#3889)

.github/workflows/checks.yml

@@ -76,7 +76,6 @@ jobs:
       - uses: actions/checkout@v3
       - name: Set up environment
         uses: ./.github/actions/setup
-      - run: rm foundry.toml # https://github.com/foundry-rs/foundry/issues/3827
       - uses: crytic/slither-action@v0.2.0
 
   codespell: