add upgrade script

scripts/upgrade.ts

@@ -0,0 +1,24 @@
+import { ethers } from "hardhat";
+
+async function main(proxyAddr:string) {
+
+  const Git3 = await ethers.getContractFactory("Git3Hub");
+  const git3 = await Git3.deploy();
+  let logicReceipt = await git3.deployed()
+
+  let proxyInstance = await ethers.getContractAt("UpgradeableProxy",proxyAddr);
+  // Proxy don't need to init Git3 contract because the constructor is empty.
+  let initSelector = "0x";
+  let [operator,] = await ethers.getSigners();
+  let receipt = await proxyInstance
+    .connect(operator)
+    .upgradeToAndCall(git3.address, initSelector);
+  await receipt.wait();
+
+  console.log("upgradeTxHash:",receipt.hash);
+}
+
+main(process.argv0).catch((error) => {
+  console.error(error);
+  process.exitCode = 1;
+});