Solution for graphql_derive build errors

I had these issues about half a year ago, and finally decided to just massage the `Cargo.toml`'s by hand until it worked.

I hereby urge you to commit `Cargo.lock`, even for libraries like this one, because `cargo` only creates `Cargo.lock` if there's _something_ lock-worthy like the examples here.

Please don't make me spend the better part of a day for the next example/experiment.

Here is what I came up with, btw.: https://gist.github.com/namibj/beb55efb68b6663cb06bbcacece61e3b
It's not pretty, due to the path dependencies, but at _compiles._

Edit: it still panics at runtime, but at least it works to some extend.