hotfix: Revert changes made in v2.6.0

[Voltra]

v2.6.0 introduced what was supposed to be Filament v4 compatibility, but breaking changes (mostly v4 namespaces related) slipped through unit tests.

This PR reverts those changes

[what-the-diff]

PR Summary

• Updated GitHub Actions workflows to use newer version of checkout action
  The GitHub Actions, which are set of instructions to automate our software workflows, have been updated to use a newer version. This change has been implemented in four different workflow files. This ensures our workflows are using the most stable and feature-rich versions.

• Changed the cache action version in one workflow file
  The cache action version has been adjusted downwards from v4 to v3 in the run-tests.yml workflow. This may increase workflow robustness or resolve potential issues from the previous version.

• Removed certain details from the changelog and README files
  We removed specific information related to the previous version v2.6.0 from the changelog and 'how-to-use' guide (README.md). This could decrease confusion or misinformation for those reading these documents.

• Adjusted dependency versions in composer.json
  Several changes have been made in our project's PHP package manager file:

  • The PHP version requirement has been restricted to version ^8.1.
  • The filament/filament dependency has been limited to support only version ^3.0 and ^4.0 compatibility has been removed.
  • The pboivin/filament-peek package now only requires version ^2.0.
  • The larastan/larastan package is now limited to version ^2.9 and no longer includes ^3.0.

These modifications give us more control over the versions of the packages our project depends on, making our project more stable and predictable.

[Voltra]

@Z3d0X ready for a hotfix release in v2.6.1

Then we can move on to a 3.x branch for Filament v4