Update create-github-release script for Octokit auth API change

Update script to authenticate using the new API documented at
https://github.com/octokit/rest.js#authentication

scripts/create-github-release.js

@@ -9,7 +9,7 @@
  * `v<VERSION>` where <VERSION> is the `version` field in package.json.
  */
 
-const octokit = require('@octokit/rest')();
+const Octokit = require('@octokit/rest');
 
 const pkg = require('../package.json');
 const { changelistSinceTag } = require('./generate-change-list');
@@ -26,9 +26,8 @@ async function createGitHubRelease() {
     throw new Error('GITHUB_TOKEN env var is not set');
   }
 
-  octokit.authenticate({
-    type: 'oauth',
-    token: process.env.GITHUB_TOKEN,
+  const octokit = new Octokit({
+    auth: `token ${process.env.GITHUB_TOKEN}`,
   });
 
   const changes = await changelistSinceTag(octokit);