Do not use dynamic properties in classes

[KadelaKuba]

WHY are these changes introduced?

In project was used dynamic properties that are deprecated in PHP 8.2

WHAT is this pull request doing?

This pull request adds missing properties to classess. Do not use dynamic properties. Create class properties instead.

Type of change

• Patch: Bug (non-breaking change which fixes an issue)
• Minor: New feature (non-breaking change which adds functionality)
• Major: Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have added a changelog entry, prefixed by the type of change noted above
• I have added/updated tests for this change
• I have updated the documentation for public APIs from the library (if applicable)

[jDolba]

Nice and easy.
We are using this fork on for a while with php 8.2 and no deprecation appearing in our error log (using only GraphQL API from PHP)

[paulomarg]

Thanks for the contribution! We fixed this along with a couple other things in #262, so I'm going to close the PR. Please do continue to contribute in the future!