Update for PHP 8.3 minimum and other improvements

[rikgirbes]

Description:
This pull request includes several updates and improvements to modernize the project:

• PHP 8.3 minimum: Updated composer.json to require PHP 8.3. https://endoflife.date/php
• Updated README: Reflects changes, added some headers.
• Removed build directory: The build/ directory has been removed as it is not required, dependencies should be handled by composer.
• Updated Composer packages: Ran composer update to ensure dependencies are up-to-date.
• Added .gitignore: Excludes build/, vendor/, IDE specific files, and other sensible defaults.
• Use Composer default bin-dir: Removed custom bin-dir, Composer defaults to vendor/bin.
• Enforce HTTPS in Composer: Ensures secure URLs for Composer repositories.

Testing:

• Verified the project runs successfully with PHP 8.3 + 8.4.
• Composer installations and updates work as expected.

[rikgirbes]

Fixes multiple issues:

#8 #5 #4 #3

[woutse]

Thanks for your pull request. We'll look into it!