fix(laravel): belongs-to-many relations dont have a get-foreign-key-name method

[mariantrifu]

Q	A
Branch?	4.2
Tickets	Closes #7587 https://github.com/api-platform/core/issues/7587
License	MIT

API Platform library tries to extract the foreign_key from all relations, but BelongsToMany relations don't have a getForeignKeyName() method, so it returns null. When API Platform tries to flip an array containing null values, PHP throws the error: array_flip(): Can only flip string and integer values, entry skipped.

[MakFly]

Hi , i have same problem , when do you think you can merge ? this fix ?

@soyuka

[soyuka]

sure thing is I need to add a test you can also just drop an example of model and request I'll add it (though any llm can do it inside the workbench and the functional tests)