Add support for PHP 8.4 and 8.5

[mpesari]

General

• Fail phpunit tests on all issues (PHP warnings, deprecations etc.)

PHP 8.4

• Run tests on PHP 8.4
• Fix deprecated use of implicitly nullable parameters
  • This feature is available since PHP 7.1, which is the lowest supported version in composer.json, so there are no backward compatibility issues
  • https://www.php.net/manual/en/migration71.new-features.php#migration71.new-features.nullable-types
  • https://www.php.net/manual/en/migration84.deprecated.php#migration84.deprecated.core.implicitly-nullable-parameter

PHP 8.5

• Run tests on PHP 8.5
• Fix deprecated use of null as array key
  • Not sure why null is used here as array key, but this doesn't change code behaviour
  • https://www.php.net/manual/en/migration85.deprecated.php#migration85.deprecated.core.using-null-as-an-array-offset
• Fix deprecated use of Reflection setAccessible()
  • The method is noop since PHP 8.1.0 and deprecated since 8.5.0
  • This changes the code to call setAccessible() only on PHP < 8.1.0, where it does something
  • https://www.php.net/manual/en/migration81.other-changes.php#migration81.other-changes.functions.reflection
  • https://www.php.net/manual/en/migration85.deprecated.php#migration85.deprecated.reflection

[SvenRtbg]

Thank you for this contribution. I don't see any issues, and the PHP version check respects the established practice.

I hope Christian has time to merge and release it.

[RobinvanderVliet]

@cweiske Could you take a look at this pull request? I've tried updating our server to PHP 8.5.1 today, and I get the following deprecation notice from this library:

Deprecated: Using null as an array offset is deprecated, use an empty string instead in /vendor/netresearch/jsonmapper/src/JsonMapper.php:757

This pull request should fix that notice.