Builder does not support all postgres operators

[markuskooche]

It is not possible to use the IS or IS NOT operators for example in the whereRelation() function.

The problem is that theIlluminate\Database\Query\Builder does not support these operators.
It would work if these operators were included in this array.

https://github.com/laravel/framework/blob/9.x/src/Illuminate/Database/Query/Builder.php#L199-L206

And the whereRelation() calls the where() function inside the builder, which changes unsupported operators to =.

https://github.com/laravel/framework/blob/9.x/src/Illuminate/Database/Query/Builder.php#L739-L741