refactor: (if|when)-let -> (if|when)-let*

With the former macros' future in the air (and likely to be targeted in
future, potentially breaking changes), I'll deal with this now than have
it bite me later.

Ref: https://lists.gnu.org/archive/html/emacs-devel/2024-10/msg00637.html

modules/lang/haskell/autoload.el

@@ -5,9 +5,9 @@
   "Opens a Haskell REPL."
   (interactive "P")
   (require 'haskell-interactive-mode)
-  (if-let (window
-           (display-buffer
-            (haskell-session-interactive-buffer (haskell-session))))
+  (if-let* ((window
+             (display-buffer
+              (haskell-session-interactive-buffer (haskell-session)))))
       (window-buffer window)
     (error "Failed to display Haskell REPL")))