Fix "Implicitly marking parameter $groups as nullable is deprecated"

[barbieswimcrew]

No description provided.

[dsbe-ak]

Hi, this breaks setting groups via annotation options for ZipCode, because now the groups are set as an empty array, which will always overwrite the options['groups'] in the original Constraint constructor for symfony 5.4

if (null !== $groups) {
    $options['groups'] = $groups;
}

In the original Constraint constructor the groups are defined as ?array $groups = null

[barbieswimcrew]

@dsbe-ak sorry... my fault... fixed that with https://github.com/barbieswimcrew/zip-code-validator/releases/tag/v3.1.4