Bugfix: Do not check for protection at the end of the line.

The end of the last line of a colon example is not protected, and this
caused the time stamp removal protection to fail if a time stamp was
the last thing in such an example.

lisp/org-exp.el

@@ -1854,6 +1854,7 @@ from the buffer."
 (defun org-export-remove-timestamps ()
   "Remove timestamps and keywords for export."
   (while (re-search-forward org-maybe-keyword-time-regexp nil t)
+    (backward-char 1)
     (org-if-unprotected
      (replace-match "")
      (beginning-of-line 1)