Add yarn.lock updated check

The CI build should verify if yarn run init was ran before the PR was opened. To do that:

1-) CI will download the target branch
2-) CI will store the md5 of the target branch yarn.lock
3-) CI will run 'yarn run init' on the target branch
2-) CI will store the md5 of the possibly changed target branch yarn.lock
5-) If the MD5s are different, CI fails