guzzle: TooManyRedirectsException after downgrading - php

Question

The code worked correctly on version 7+, however, when the version is downgraded to 6, the function falls with an error.
Code:
<?
define(ZIP_TO_LOCATION_APP, "https://tools.usps.com/tools/app/ziplookup/cityByZip");
function get_location_from_zip($zip_code) {
$client = new GuzzleHttp\Client();
$response = $client->request("POST", ZIP_TO_LOCATION_APP, [
'form_params' => [
'zip' => $zip_code
]
]);
if ($response->getStatusCode() == 200) {
$contents = $response->getBody()->getContents();
$contents = json_decode($contents, true);
$contents["error"] = false;
return $contents;
} else {
return array(
"error" => true
);
}
}
Output:
Fatal error: Uncaught GuzzleHttp\Exception\TooManyRedirectsException: Will not follow more than 5 redirects in C:\OpenServer\domains\job-board.loc\api\classes\composer\vendor\guzzlehttp\guzzle\src\RedirectMiddleware.php:159 Stack trace: #0 C:\OpenServer\domains\job-board.loc\api\classes\composer\vendor\guzzlehttp\guzzle\src\RedirectMiddleware.php(94): GuzzleHttp\RedirectMiddleware->guardMax(Object(GuzzleHttp\Psr7\Request), Array) #1 C:\OpenServer\domains\job-board.loc\api\classes\composer\vendor\guzzlehttp\guzzle\src\RedirectMiddleware.php(72): GuzzleHttp\RedirectMiddleware->checkRedirect(Object(GuzzleHttp\Psr7\Request), Array, Object(GuzzleHttp\Psr7\Response)) #2 C:\OpenServer\domains\job-board.loc\api\classes\composer\vendor\guzzlehttp\promises\src\FulfilledPromise.php(41): GuzzleHttp\RedirectMiddleware->GuzzleHttp\{closure}(Object(GuzzleHttp\Psr7\Response)) #3 C:\OpenServer\domains\job-board.loc\api\classes\composer\vendor\guzzlehttp\promises\src\TaskQueue.php(48): GuzzleHttp\Promise\FulfilledPromise::GuzzleHttp\Promis in C:\OpenServer\domains\job-board.loc\api\classes\composer\vendor\guzzlehttp\guzzle\src\RedirectMiddleware.php on line 159
I tried playing around with the allow_redirects option, this can hide the exception, but it still doesn't return a response.