Fix encoding arrays for (NOT) IN queries

[JulianVennen]

When trying to use a where condition, using IN or NOT IN and passing an array, the following Fatal Error occurs:

PHP Fatal error:  Uncaught TypeError: Aternos\Model\Query\Generator\SQL::generateValue(): Argument #1 ($value) must be of type string|int|float|null, array given, called in vendor/aternos/model/src/Query/Generator/SQL.php on line 127 and defined in vendor/aternos/model/src/Query/Generator/SQL.php:267
Stack trace:
#0 vendor/aternos/model/src/Query/Generator/SQL.php(127): Aternos\Model\Query\Generator\SQL->generateValue()
#1 vendor/aternos/model/src/Query/Generator/SQL.php(145): Aternos\Model\Query\Generator\SQL->generateWhere()
#2 vendor/aternos/model/src/Query/Generator/SQL.php(88): Aternos\Model\Query\Generator\SQL->generateWhere()
#3 vendor/aternos/model/src/Driver/Mysqli/Mysqli.php(240): Aternos\Model\Query\Generator\SQL->generate()
#4 vendor/aternos/model/src/GenericModel.php(469): Aternos\Model\Driver\Mysqli\Mysqli->query()

This PR fixes that issue by generating the correct SQL representation of the array