Add PHP 8.4 to build matrix

[DannyvdSluijs]

This pull request includes a small change to the .github/workflows/main.yml file. The change adds support for PHP version 8.4 to the CI workflow.

• .github/workflows/main.yml: Added PHP version 8.4 to the matrix of versions to test in the CI workflow.

It might very well be that when the pipeline is executed some deprecations might pop up. If any show up I am willing to spend some additional time in getting them resolved.

[PowerKiKi]

Thank you, released as https://github.com/genkgo/camt/releases/tag/2.8.1