bump version to 0.5.6.0

changelog

 -*-change-log-*-
 
+0.5.6.0 Ross Paterson <R.Paterson@city.ac.uk> Feb 2019
+	* Generalized type of except
+	* Added Control.Monad.Trans.Writer.CPS and Control.Monad.Trans.RWS.CPS
+	* Added Contravariant instances
+	* Added MonadFix instance for ListT
+
 0.5.5.0 Ross Paterson <R.Paterson@city.ac.uk> Oct 2017
 	* Added mapSelect and mapSelectT
 	* Renamed selectToCont to selectToContT for consistency

transformers.cabal

 name:         transformers
-version:      0.5.5.0
+version:      0.5.6.0
 license:      BSD3
 license-file: LICENSE
 author:       Andy Gill, Ross Paterson