fix: solium errors - blank-line only

contracts/mocks/SecureTargetBounty.sol

@@ -1,6 +1,5 @@
 pragma solidity ^0.4.18;
 
-
 import {Bounty, Target} from "../../contracts/Bounty.sol";
 
 
@@ -10,6 +9,7 @@ contract SecureTargetMock is Target {
   }
 }
 
+
 contract SecureTargetBounty is Bounty {
   function deployContract() internal returns (address) {
     return new SecureTargetMock();