Fix parameter $checkDigit as nullable is deprecated

What's Changed

• Test PHP 8.4 by @Ekman in #45
• Fix PHP 8.4 deprecation warning "Implicitly marking parameter $checkDigit as nullable is deprecated" in Number by @Horat1us in #44

New Contributors

• @Horat1us made their first contribution in #44

Full Changelog: 5.0.1...5.0.2

PHP 8.1

Implement new __serialize() and __unserialize() functions. Silences:

PHP Deprecated:  Nekman\LuhnAlgorithm\Number implements the Serializable interface, which is deprecated. Implement __serialize() and __unserialize() instead (or in addition, if support for old PHP versions is necessary) in luhn-algorithm\src\Number.php on line 39

PHP 8 support

• Increased upper PHP version to 8
• Increased lower PHP version to 7.4
• Properly type hinting NumberInterface::getCheckDigit() return
• Added throws LuhnAlgorithmExceptionInterface to all functions

Migrating from v4 to v5

There's a high probability that this change is not breaking for you

1. Make sure your application runs and supports PHP >= 7.4
2. If you've implemented NumberInterface, then add ?int to the getCheckDigit() return
3. If you want to, catch LugnAlgorithmExceptionInterface

Exception handling

• Add ArgumentIsNotNumericException and MissingCheckDigitException
• Add @throws MissingCheckDigitException to the facade isValid method clearly explaining that it can be thrown from there. Old code is still compatible due to MissingCheckDigitException extending \InvalidArgumentException
• Update copyright notice
• Implement \Serializable on Number

Update copyright notice

Update the copyright notice

PHP 7.3

Changes to this release:

• Run tests on PHP 7.3
• Improve tests by adding purpose

Lower the minimum PHP version to 7.0

• Lower the minimum PHP version to 7.0

Numbers larger than PHP_INT_MAX

• Fixed implementation not working for numbers larger than PHP_INT_MAX.

Minor fixes to new implementation.

• Declare strict types.
• Minor bug fix to calculating checksum.
• Add test for InvalidArgumentException in validation method.
• Update readme.
• Update travis build process.

Rewrite of the implementation

• The Luhn Algorithm implementation has been completely rewritten.
• Added a NumberInterface contract in order to properly separate the number with the check digit.