Add CI run on specific apache/dolphinscheduler pr instead of dev one

Sometimes we may create a PR base on apache/dolphinscheduler change, but DolphinScheduler-sdk-python only can run on dev head ref commit, we should find out a way to run on specific apache/dolphinscheduler pr to make our CI more smooth. I have a POC in https://github.com/apache/dolphinscheduler-sdk-python/pull/9/commits/93e7de420c57e518860cb06b2caa749b5af3d5f2, it work but not pretty.

If we can change the PR number from a comment or a commit message instead of directly change CI constants will be prefect