I see that you already have 25 contributors, so you might wanna try filing an issue asking for someone to take over. A very good advice I've gotten is to grant commit access to anyone who files a PR that gets merged[0].

The best person to take over is probably in this list[1].

[0]: http://felixge.de/2013/03/11/the-pull-request-hack.html

[1]: https://github.com/eneifert/ZendeskApi_v2/graphs/contributor...