bug#65768: Bump persist.el version

[Stefan Kangas]

BTW, I see the following warnings from package-lint:

1:64: warning: You should depend on (emacs "24.1") if you need lexical-binding.
228:51: error: You should depend on (emacs "26.1") if you need `recordp'.
233:64: error: You should depend on (emacs "26.1") if you need `recordp'.
236:53: error: You should depend on (emacs "26.1") if you need `recordp'.

Would the below patch be appropriate?

diff --git a/persist.el b/persist.el
index 2b96b2b7f0..6cc94b4db3 100644
--- a/persist.el
+++ b/persist.el
@@ -5,6 +5,7 @@
 ;; Author: Phillip Lord <phillip.lord@russet.org.uk>
 ;; Maintainer: Joseph Turner <persist-el@breatheoutbreathe.in>
 ;; Package-Type: multi
+;; Package-Requires: ((emacs "26.1"))
 ;; Version: 0.6

 ;; The contents of this file are subject to the GPL License, Version 3.0.