fix: core tests ci workflow

Author: arwer13

.github/workflows/core_tests.yml

@@ -26,6 +26,8 @@ jobs:
           ETH_RPC_URL: "https://mainnet.infura.io/v3/${{ secrets.WEB3_INFURA_PROJECT_ID }}"
 
     steps:
+      - uses: actions/checkout@v4
+
       - name: Check that the fork is ready
         shell: bash
         run: timeout 30 bash -c 'until printf "" 2>>/dev/null >>/dev/tcp/$0/$1; do sleep 1; done' 127.0.0.1 8555