conversion-fn calls itself with wrong arity

[jafingerhut]

https://github.com/ztellman/byte-streams/blob/master/src/byte_streams/graph.clj#L210

Found using unreleased version of Eastwood, with fixes not discovered necessary until I tried linting the byte-streams library.

[ztellman]

Ha, interesting, that code path wasn't being used due to an unrelated issue, making the code correct but not in the intended way. Thanks.