Curly brace syntax for accessing array elements and string offsets has been deprecated in PHP 7.4

The provided works correctly on PHP 8.1+.

As this issue has been open for a while, and myself and others have tested and confirmed that this is working, I'm going to mark this as reviewed and tested now.

Patch applied and included in release Bbcode 7.x-4.0.

Automatically closed - issue fixed for 2 weeks with no activity.