pom: update to oncrpc4j-2.3.1

Changelog for oncrpc4j-2.2.0..oncrpc4j-2.3.1
    * [a3c4887] portmap: add OncRpcEmbeddedPortmap#shutdown()
    * [600a3f9] libs: switch to grizzly-2.3.12
    * [47a05a3] core: update grizzly thread pool sizes to best-practice configuration
    * [9a9e489] libs: use spring 4.0.3
    * [785fbd0] rpc: allow async request processing
    * [4761a81] gss: auto-generate jass configuration file to simplify initialization
    * [7c9dcaa] svc: move gss initialization into OncRpcSvcBuilder
    * [d839afa] rpc: use mockito to mock Connection
    * [defe79c] rpc: do not keep reference to context in transport
    * [af738cd] rpc: remove Selector form the name thread name
    * [b67a30b] rpc: add a possibility to inject worker thread pool

Acked-by: Gerd Behrmann
Target: master, 0.9, 0.8
(cherry picked from commit 66c91af5fcd388efe1c51f5573c7e823b79162cb)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>