test: ffi: speed up

Author: elopez

tests/solidity/cheat/ffi.sol

@@ -11,10 +11,10 @@ contract TestFFI {
 
   function foo(int x) external {
     string[] memory inputs = new string[](3);
-    inputs[0] = "python3";
+    inputs[0] = "sh";
     inputs[1] = "-c";
     // ABI encoded "gm", as a string
-    inputs[2] = "print('0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002676d000000000000000000000000000000000000000000000000000000000000', end='')";
+    inputs[2] = "printf '%s' '0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002676d000000000000000000000000000000000000000000000000000000000000'";
 
     bytes memory res = Hevm(HEVM_ADDRESS).ffi(inputs);