Use cl-gentemp in another place

This avoids "Variable unknown" errors if a byte-compiled init.elc happening to
encounter an error while evaluating an :init or :config block.

lisp/use-package/use-package-core.el

@@ -1021,7 +1021,7 @@ meaning:
       use-package--hush-function)))
 
 (defun use-package-handler/:catch (name keyword arg rest state)
-  (let* ((context (cl-gensym "use-package--warning")))
+  (let* ((context (cl-gentemp "use-package--warning")))
     (cond
      ((not arg)
       (use-package-process-keywords name rest state))