renovate.json

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "extends": ["config:base"],
  "customManagers": [
    {
      "customType": "regex",
      "fileMatch": ["Formula(/\\S+)?/\\S+\\.rb"],
      "matchStrings": [
        "#\\s?renovate:?\\s*(registryUrl=(?<registryUrl>.+))?\\s*\\n\\s*depends_on \"https://raw.githubusercontent.com/(?<repo>[A-Za-z0-9-_]+/[A-Za-z0-9-_]+)/(?<currentValue>[A-Za-z0-9]+)/(?<depName>.+).rb\""
      ],
      "versioningTemplate": "{{# if versioning}}{{{versioning}}}{{else}}git{{/if}}",
      "datasourceTemplate": "custom.github-file"
    }
  ],
  "customDatasources": {
    "github-file": {
      "defaultRegistryUrlTemplate": "https://api.github.com/repos/{{repo}}/commits?path={{packageName}}.rb",
      "transformTemplates": [
        "{\"releases\":[{\"version\": $$.[0].sha, \"releaseTimestamp\": $$.[0].commit.author.date}]}"
      ]
    }
  }
}