Import ERC20PresetMinterPauser for migrations

contracts/Migrations.sol

@@ -1,19 +1,24 @@
-// SPDX-License-Identifier: MIT
-pragma solidity >=0.4.22 <0.8.0;
+pragma solidity =0.6.12;
+import "@openzeppelin/contracts/presets/ERC20PresetMinterPauser.sol";
 
 contract Migrations {
-  address public owner = msg.sender;
+  address public owner;
   uint public last_completed_migration;
 
   modifier restricted() {
-    require(
-      msg.sender == owner,
-      "This function is restricted to the contract's owner"
-    );
-    _;
+    if (msg.sender == owner) _;
+  }
+
+  constructor() public {
+    owner = msg.sender;
   }
 
   function setCompleted(uint completed) public restricted {
     last_completed_migration = completed;
   }
+
+  function upgrade(address new_address) public restricted {
+    Migrations upgraded = Migrations(new_address);
+    upgraded.setCompleted(last_completed_migration);
+  }
 }