Add virtual environment checking for Ubuntu 22.04

GitHub Actions recently provides public beta version of Ubuntu 22.04
actions/runner-images#5490

This change set just adds environment checking matrix for further changes.

.github/workflows/ci.yml

@@ -666,6 +666,7 @@ jobs:
  matrix:
  include: [
  { os: ubuntu-latest, }, # https:/actions/virtual-environments/
+ { os: ubuntu-22.04, }, # https:/actions/virtual-environments/blob/main/images/linux/Ubuntu2204-Readme.md
  { os: ubuntu-20.04, }, # https:/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-Readme.md
  { os: ubuntu-18.04, }, # https:/actions/virtual-environments/blob/main/images/linux/Ubuntu1804-Readme.md
  ]