Use below query on Google public github archive dataset:
SELECT repo.name
, MAX(CAST(JSON_EXTRACT_SCALAR(payload, '$.pull_request.base.repo.stargazers_count')AS INT64)) stars
FROM `githubarchive.month.201912`
WHERE JSON_EXTRACT_SCALAR(payload, '$.pull_request.base.repo.language') = 'Ruby'
AND type='PullRequestEvent'
GROUP by repo.name
ORDER BY stars DESC