mtl-2.3.1

2.3.1 -- 2022-10-31

• Add modifyError to Control.Monad.Error.Class, and re-export from
  Control.Monad.Except.
• Make the MonadCont instance for ContT more polykinded; now, r is allowed
  to be of an arbitrary kind k, rather than only Type.
• Add a generic liftCallCC for use with any MonadTrans.
• Return re-export of ExceptT and related functions to Control.Monad.Except.
• Add label function to MonadCont