I don't think it is available on Debian Stretch, unfortunately (this is one of the down sides of running Debian stable, and similar distros: very stable, but you'll find it difficult to get the most recent packages). What you could try (if you don't mind the potential loss of "stability" that comes with it) is updating to Debian testing. Another option (but I haven't used Debian in a long time, so am not sure) is trying to use the Ubuntu PPA on Debian, but I would expect this to be a lot more difficult / not work at all (I don't know how this would work with dependencies).