Update README.md

Author: reshadman

README.md

@@ -8,7 +8,7 @@ Adds optimistic locking feature to Eloquent models.
 composer require reshadman/laravel-optimistic-locking
 ```
 
-> This package supports Laravel 5.5.* and 5.6.* .
+> This package supports Laravel 5.5.*,  5.6.* and 5.7.* .
 
 ## Usage