remove lexical-let

Author: Danny McClanahan

markdown-mode.el

@@ -6061,8 +6061,7 @@ the rendered output."
     markdown-live-preview-view-buffer))
 
 (defun markdown-live-preview-update (buf)
-  (lexical-let ((buf buf))
-    (lambda () (with-current-buffer buf (markdown-live-preview-async-export)))))
+  (lambda () (with-current-buffer buf (markdown-live-preview-async-export))))
 
 (defun markdown-live-preview-setup ()
   (setq markdown-live-preview-current-buffer-sync-async