Use NPM to manage their versions: manually vendoring the libraries isn't feasible for Octokit, as its libraries aren't provided as single-file imports, and have nested dependencies of their own. Since NPM is needed to resolve that, use it for the other dependencies too.
Hugo's built-in bundling and minification support is used, though it means that the dependencies are duplicated within the scripts imported on different pages. I think that could be avoided by introducing a middle layer of JS assets that bundle the dependencies but aren't bundled themselves.