fix: correct syntax for API_KEY_ARBISCAN in GitHub Actions workflow

Author: tnkshuuhei

.github/workflows/test.yml

@@ -11,7 +11,7 @@ env:
   API_KEY_OPTIMISTIC_ETHERSCAN: ${{secrets.API_KEY_OPTIMISTIC_ETHERSCAN}}
   API_KEY_ETHERSCAN: ${{secrets.API_KEY_ETHERSCAN}}
   API_KEY_ALCHEMY: ${{secrets.API_KEY_ALCHEMY}}
-  API_KEY_ARBISCAN: ${{${{secrets.API_KEY_ARBISCAN}}
+  API_KEY_ARBISCAN: ${{secrets.API_KEY_ARBISCAN}}
   API_KEY_BASESCAN: ${{secrets.API_KEY_BASESCAN}}
   API_KEY_CELOSCAN: ${{secrets.API_KEY_CELOSCAN}}