Set minimum required pragma (#127)

Set minimum required pragma in`ERC20Mock`

Author: james-toussaint

contracts/mocks/token/ERC20Mock.sol

@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: MIT
-pragma solidity ^0.8.24;
+pragma solidity ^0.8.20;
 
 import {ERC20, ERC1363} from "@openzeppelin/contracts/token/ERC20/extensions/ERC1363.sol";