How to disable foreign keys constraints in postgresql during Laravel Testing

I have a lot of unit tests with many factories. But due to foreign keys I need even more factories in each test.

Is it possible to disable foreign keys during testing? I tried to use 'foreign_key_constraints' => false, but there are no effects.

    'pgsql_testing' => [
        'driver' => 'pgsql',
        'host' => env('DB_HOST_TESTING', '127.0.0.1'),
        'port' => env('DB_PORT_TESTING', '5432'),
        'database' => env('DB_DATABASE_TESTING', 'forge'),
        'username' => env('DB_USERNAME_TESTING', 'forge'),
        'password' => env('DB_PASSWORD_TESTING', ''),
        'charset' => 'utf8',
        'prefix' => '',
        'schema' => 'public',
        'sslmode' => 'prefer',
        'foreign_key_constraints' => false, //does not help
    ],

I use PostgreSQL 10.7 and Laravel 5.8