Update AUTHORS and CHANGELOG for previous commit

AUTHORS.md

@@ -48,4 +48,5 @@
 -   ([@rmadsen-ks](https://github.com/rmadsen-ks))
 -   ([@stonebig](https://github.com/stonebig))
 -   ([@testrunner123](https://github.com/testrunner123))
+-   ([@GSPP](https://github.com/GSPP))
 

CHANGELOG.md

@@ -31,6 +31,7 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 -   Fixed `clr.GetClrType` when iterating over `System` members (#607) 
 -   Fixed `LockRecursionException` when loading assemblies (#627)
 -   Fixed errors breaking .NET Remoting on method invoke (#276)
+-   Fixed PyObject.GetHashCode (#676)
 
 
 ## [2.3.0][] - 2017-03-11