drop support for spatie permission 5.0 and add support for 6.0

[bezhanSalleh]

fixes #272

[what-the-diff]

PR Summary

• Updates to README.md file
  The README.md file, which provides useful information about the project, has been updated. We've included two new pieces of important information: a direct link to the 2.x version of this project and specific notes about changes that could potentially affect the behaviour of your existing code when you decide to migrate from the current version.

• Modification in composer.json file
  We updated the spatie/laravel-permission version dependency in our project settings (specifically the composer.json file). Instead of the older 5.0 version, we're now using the newer, more robust 6.0 version. This change helps make sure we're utilizing the protection instructions in the most effective and up-to-date manner.