chore(CI): bump to ubuntu 22.04 runner

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     # Machine environment:
     # https://help.github.com/en/articles/software-in-virtual-environments-for-github-actions#ubuntu-1804-lts
     # We specify the Node.js version manually below, and use versioned Chrome from Puppeteer.
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-22.04
 
     steps:
       - uses: actions/checkout@v1