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/tools/lsp/autoload/lsp-mode.el

@@ -5,7 +5,7 @@
 (defun set-lsp-priority! (client priority)
   "Change the PRIORITY of lsp CLIENT."
   (require 'lsp-mode)
-  (if-let (client (gethash client lsp-clients))
+  (if-let* ((client (gethash client lsp-clients)))
       (setf (lsp--client-priority client)
             priority)
     (error "No LSP client named %S" client)))