Normalising array braces in old version

[ttomdewit]

Dear @milon 👋,

I'm using a somewhat outdated version at 5.3.6 (working on fixing that ASAP) but in the meantime I started working on a PR (https://github.com/ttomdewit/barcode/tree/normalize-index-braces) to fix some deprecated code on php 7.4 for the latest tag in the 5.3.* series.

I don't know how to create an MR against that specific version, will you be willing to help and assist to get this merged?

Thank you for your time!