Added a fix for country validation made by @julesdohmen

• fix: integer overflow on 32 bit architectures (#137)
• chore: update github actions to run tests on PHP 8.X versions
• feat: migrate composer to 2.0
• chore: Informing users about problem validating UK VAT ID's (#126)
• chore: Replace abandoned Sensiolabs security checker

With Brexit being final, we like to welcome Northern Ireland to the VAT validation service. A huge thanks for @jonathanmaron to provide the update to make this possible.

The country code for Northern Ireland is XI, but the original VAT ID's remain the same as they were for the UK.

This release was long overdue but because of work, life and Covid-19 a delay was unfortunately not preventable.

With this release we have a few new features and some bug fixes:

• Using the command line for checking VAT
• Full support for proxy services
• Allowing to use VIES test codes
• Allowing VAT for Bulgarian foreign natural persons

This release was made possible thanks to the help of @jellynoone and @fabianwelzer. Great work folks 👍 and thank you for your contributions 🙇!

It has taken a while but this release is jam-packed with bug fixes and improvements.

Here's a list of what has been done:

• Bug fixes:
  • Issue #99: Failure to add arguments (like trader name) with non-Latin characters
  • Issue #64: Adding support for VIES Test services
• Improvements:
  • Removing support for PHP-7.0
  • Improving unit and integration tests
  • Added additional edge test cases
  • Improving language usage and error messages
  • Moving Docker containers into their own project space

A huge thanks and appreciation for @peter279k for his pull requests and to @krzaczek, @robmeek, @fidelo-software and @MPablo for reporting issues. Thank you all 🙇 for your time and efforts.

Enjoy this new release 🚀

Minor updates:

• Added VAT validation for new Dutch ID's for self employed entrepreneurs
• Added support for PHP 7.4 in testing

A big shoutout this time to @krzaczek for his swift actions and code updates, but also a big thank you to @Smitsel and @MollieRick for their contributions in getting this change mentioned and updated.