[9.x] Fix Support\Collection reject method type definition

[joecampo]

This PR fixes the type definition for the reject collection method.

The reject method also passes the $key to the closure as the second param.

$collection = collect([1, 2, 3, 4]);
 
$filtered = $collection->reject(function ($value, $key) {
    return $value > 2;
});
 
$filtered->all();
 
// [1, 2]