Implicitly nullables parameters are deprecated in PHP 8.4

[david-zelty]

Describe the bug
Since PHP 8.4, implicitly nullables parameters are deprecated. I found 2 files in the sdk that will throw a deprecation in php 8.4 : EvaluationReason@169 & EvalResult@25 .

To reproduce
Run sdk on php 8.4

Expected behavior
No deprecation should be thrown.

SDK version
6.5

Language version, developer tools
PHP 8.4

OS/platform
Any

[david-zelty]

Please concider this pull request as a possible solution :)

[keelerm84]

Released in v6.5.1