Integer as value in IncidentsClientDecorator throws TypeError

[brotkrueml]

Exception trace:

PHP Fatal error:  Uncaught TypeError: Argument 2 passed to Buzz\Browser::prepareMultipart() must be of the type string, int given, called in /xxx/vendor/kriswallsmith/buzz/lib/Browser.php on line 127 and defined in /xxx/vendor/kriswallsmith/buzz/lib/Browser.php:219
Stack trace:
#0 /xxx/vendor/kriswallsmith/buzz/lib/Browser.php(127): Buzz\Browser->prepareMultipart()
#1 /xxx/vendor/brotkrueml/jobrouter-client/src/Client/RestClient.php(200): Buzz\Browser->submitForm()
#2 /xxx/vendor/brotkrueml/jobrouter-client/src/Client/RestClient.php(156): Brotkrueml\JobRouterClient\Client\RestClient->sendForm()
#3 /xxx/start_instance.php(48): Brotkrueml\JobRouterClient\Client\RestClient->request()
#4 {main}
  thrown in /xxx/vendor/kriswallsmith/buzz/lib/Browser.php on line 219

Example:

$multipart = [
    'step' => '1',
    'summary' => 'Instance started via JobRouter Client',
    'processtable[fields][0][name]' => 'NAME',
    'processtable[fields][0][value]' => 'Max Mustermann',
    'subtables[0][name]' => 'KNOWLEDGE',
    'subtables[0][rows][0][fields][0][name]' => 'SUBJECT',
    'subtables[0][rows][0][fields][0][value]'=> 'Excel',
    'subtables[0][rows][0][fields][1][name]' => 'SELF_ASSESSMENT',
    'subtables[0][rows][0][fields][1][value]'=> 2,
];

$response = $client->request(
    'POST',
    'application/incidents/application',
    $multipart
);

Solution would be to cast an integer to a string for subtables.