The previous implementation used a futures_cpupool for executing
blocking juniper operations. This pool comes in addition to the
thread pool started by hyper through tokio for executing hyper's futures.
This patch uses tokio::blocking to perform the blocking juniper
operations while re-using the same thread pool as hyper, which
simplifies the API.
* Bump` juniper`, `juniper_codegen`, and `juniper_tests` versions.
* Bump integration crate requirements to include 0.10.0. `juniper_iron` gets a semver breaking version as it has a breaking change but `juniper_iron` does not.
* Move `juniper_rocket` changelog into one file. This aligns with `juniper_iron` and will be easier
to automate in the future.
* Let `juniper_warp` and `juniper_hyper` use `0.9.x` versions of Juniper. They don't rely on anything in 0.10.0 so don't require it.
