GHPRB Job DSL for pipelines breaks with Job DSL >= 1.70

GHPRB Job DSL for pipelines breaks with Job DSL >= 1.70

If I understand correctly, the GHPRB Job DSL example tracks the GitHub repo specified in the `scm`, `git`, `remote` context - see the example Job DSL below taken from the plugin site.

However, support for the `scm{}` context (and others) has been dropped for Pipeline Jobs in Job DSL 1.70 (see https://github.com/jenkinsci/job-dsl-plugin/wiki/Migration#migrating-to-170).

If `scm{}` is deprecated, it would seem that the remote for tracking must be specified some other way.

```
pipelineJob('example') {
scm {
git {
remote {
github('test-owner/test-project')
refspec('+refs/pull/*:refs/remotes/origin/pr/*')
}
branch('${sha1}')
}
}
triggers {
githubPullRequest {
admin('user_1')
admins(['user_2', 'user_3'])
userWhitelist('you@you.com')
userWhitelist(['me@me.com', 'they@they.com'])
orgWhitelist('my_github_org')
orgWhitelist(['your_github_org', 'another_org'])
cron('H/5 * * * *')
triggerPhrase('OK to test')
onlyTriggerPhrase()
useGitHubHooks()
permitAll()
autoCloseFailedPullRequests()
allowMembersOfWhitelistedOrgsAsAdmin()
extensions {
commitStatus {
context('deploy to staging site')
triggeredStatus('starting deployment to staging site...')
startedStatus('deploying to staging site...')
statusUrl('http://mystatussite.com/prs')
completedStatus('SUCCESS', 'All is well')
completedStatus('FAILURE', 'Something went wrong. Investigate!')
completedStatus('PENDING', 'still in progress...')
completedStatus('ERROR', 'Something went really wrong. Investigate!')
}
}
}
}
}
```

Read the Job DSL 1.70 migration note linked in the issue and compare it with the embedded pipelineJob example. Trace the plugin's pipeline SCM configuration entry point, then identify a supported replacement and verify the example with Job DSL >=1.70; it is done when the documented DSL no longer relies on the removed scm context.

Written by the indexing model from the issue text.