push 時に build

[technote-space]

pr では master で build されないため build status がとれない

https://help.github.com/en/articles/events-that-trigger-workflows#pull-request-events-for-forked-repositories

If you intend to use the pull_request event to trigger CI tests, we recommend that you set up your workflow configuration to listen to the push event.

on:
  push:
    branches:
      - "*"
    tags:
      - "!*"