* Fix exceptions on ReflectionUnionTypes
this commit fixes exceptions thrown on ReflectionUnionType::isBuiltIn() and ReflectionUnionType::getNme() called on php8 union types
* Fix exceptions on ReflectionUnionTypes
this commit fixes exceptions thrown on ReflectionUnionType::isBuiltIn() and ReflectionUnionType::getNme() called on php8 union types
* add check for php8.0
* fix static analysis error
* fix $types variable undefined
* fix failing test
* fix failing test
* fixed style with php-cs-fixer
* add test for union types in parameters and return type
* add test for nullable union types in parameters and return type
* updated CHANGELOG.md
