Authorization Required on Twitter Stream Api using Guzzle PHP - oauth

Question

I want to use the Twitter Streaming Api with the filter query.
And following the GuzzleHttp documentation I'm accessing like this:
<?php
use GuzzleHttp\Client;
use GuzzleHttp\HandlerStack;
use GuzzleHttp\Subscriber\Oauth\Oauth1;
$stack = HandlerStack::create();
$middleware = new Oauth1([
'consumer_key' => 'my_key',
'consumer_secret' => 'my_secret',
'token' => 'my_token',
'token_secret' => 'my_token_secret'
]);
$stack->push($middleware);
$client = new Client([
'base_uri' => 'https://stream.twitter.com/1.1/',
'handler' => $stack,
'auth' => 'oauth'
]);
$client->post('statuses/filter.json', [
'form_params' => [
'track' => 'some_word_to_track',
],
]);
But when executing this code, I'm getting the following exception:
PHP Fatal error: Uncaught GuzzleHttp\Exception\ClientException:
Client error: 'POST https://stream.twitter.com/statuses/filter.json'
resulted in a '401 Authorization Required' response
in /Users/.../vendor/guzzlehttp/guzzle/src/Exception/RequestException.php:111
Conclusion:
Is it because I cannot use GuzzleHttp's Oauth1 Subscriber with
Twitter streaming API?
Or is it because I missing something on the
authentication?