Tag Laravel 5.8.0 release

[judgej]

Would you be able to add the 5.8.0 release to the commit that is compatible with Laravel 5.8?

The commit is:

65deec7

I realised we have been using dev-master for some time for the L 5.8 compatibility, and the L 6.0 updates have broken that. Thanks.

[judgej]

We have forked this repo just to add the tag for us, but I'm sure it will be useful to others still managing some legacy application:

https://github.com/consilience/notification/releases/tag/5.8.0