Trigger update on ecma262 push and PR

[arai-a]

depends on #14

Possible solutions:

• Use repository_dispatch [1] , and directly trigger update from ecma262 repo
• Use issue_comment [2] , and post issue comment from ecma262 repo
• Move the workflow to ecma262 repo, and push from there

[1] https://help.github.com/en/actions/reference/events-that-trigger-workflows#external-events-repository_dispatch
[2] https://help.github.com/en/actions/reference/events-that-trigger-workflows#issue-comment-event-issue_comment

[arai-a]

repository_dispatch will need Personal Access Token to trigger update workflow, and I guess that doesn't fit for the case if the consumer code is hosted on public repo.
https://help.github.com/en/actions/configuring-and-managing-workflows/creating-and-storing-encrypted-secrets
secret needs to be stored encrypted.

[arai-a]

I'm not sure how much beneficial to construct this, given:

• update takes up to 5 minutes
• gh-pages deployment takes 10 minutes or more to get reflected

So, there won't be so much difference in the latency, compared to updating every 30 minutes.

the only benefit here is that we can avoid unnecessary workflow running.