CI: macOS jobs broken due to using old haskell/actions/setup action

[RyanGlScott]

A recent CI failure that I have observed in certain macOS jobs (example):

Warning: As of 2023-09-09, haskell/action/setup is no longer maintained, please switch to haskell-actions/setup (note: dash for slash).
***************************************************************************
**                                                                       **
**              This action is DEPRECATED.                               **
**                                                                       **
**              Please use haskell-actions/setup instead.                **
**                                                                       **
**              (Note the dash instead of the slash.)                    **
**                                                                       **
***************************************************************************
Preparing to setup a Haskell environment
Preparing ghc environment
Installing ghc version 9.2.8
Error: All install methods for ghc 9.2.8 failed

I suspect that this will be fixed if we switch to haskell-actions/setup, as recommended in the deprecation warning.