Bump tested version

[Brugman]

The plugin still seems to work just fine, and that hideous notice on dot org is undesirable, so let's bump the tested version.

It seems this project goes mostly unnoticed. I wouldn't mind keeping an eye on version compatibility if you could send a license my way. 😉

[freekmurze]

@Brugman send a mail to support@spatie.be and we'll get it sorted 👍

Thanks for this PR.