bump tested wp version to 6.8

Author: dannyvankooten

readme.txt

@@ -3,7 +3,7 @@ Contributors: Ibericode, DvanKooten, hchouhan, lapzor
 Donate link: https://www.mc4wp.com/contribute/#utm_source=wp-plugin-repo&utm_medium=mailchimp-for-wp&utm_campaign=donate-link
 Tags: mailchimp, subscribe, email, newsletter, form
 Requires at least: 4.6
-Tested up to: 6.7
+Tested up to: 6.8
 Stable tag: 4.10.3
 License: GPL-3.0-or-later
 License URI: http://www.gnu.org/licenses/gpl-3.0.html