Improve current GitHub action workflows

[mattwang44]

After #102 is merged, there are still some tasks need to be done.

• Update the URL of the github page on README
• The PR for syncing with CPython opened by github action
  • It should be a draft PR before someone confirm it's fine to merge it.
  • It does not trigger CI workflow due to this issue. Consider using any one of the workarounds.
• .po files newly-created by the action has empty Language value in the header, which make CI failed. Find a method to automatically insert the value zh_TW is desired.

  "Language: \n"       # incorrect and make the CI failed
  "Language: zh_TW\n"  # correct