feat(scripts): add upgrade script

This introduces a simple upgrade script template that can be used to
upgrade the stake manager.

script/UpgradeRewardsStreamerMP.s.sol

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.26;
+
+import { UUPSUpgradeable } from "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
+import { BaseScript } from "./Base.s.sol";
+import { RewardsStreamerMP } from "../src/RewardsStreamerMP.sol";
+import { IStakeManagerProxy } from "../src/interfaces/IStakeManagerProxy.sol";
+
+contract UpgradeRewardsStreamerMPScript is BaseScript {
+    function run(address admin, IStakeManagerProxy currentImplProxy) public {
+        address deployer = broadcaster;
+        if (admin != address(0)) {
+            deployer = admin;
+        }
+        vm.startBroadcast(deployer);
+        // Replace this with actual new version of the contract
+        address nextImpl = address(new RewardsStreamerMP());
+        bytes memory initializeData;
+        UUPSUpgradeable(address(currentImplProxy)).upgradeToAndCall(nextImpl, initializeData);
+        vm.stopBroadcast();
+    }
+}