【PHP】Twitter Oauth2.0を利用したログインがうまくいかない

PHPでTwitter Oauth2.0を利用したログインの実装で、「Authorize app」クリック後、callback URLに遷移すると下記のようなエラーが出ます。

{"error":"invalid_request","error_description":"Missing required parameter [grant_type]."}int(1)

ソースコードは下記です。どのようにすればうまくいくか、わかる方いたら教えていただけると助かります。

PHP
<?php
  session_start();

  define('Consumer_Key', '<Consumer Key>');
  define('Consumer_Secret', 'Consumer Secret');
  define('Callback', 'http://127.0.0.1:3000/callback.php');
  define('Client_id', 'Client ID');

  $base_url = 'https://twitter.com/i/oauth2/authorize';

  $query = [
    'response_type' => 'code',
    'client_id' => Client_id,
    'redirect_uri' => Callback,
    'scope' => 'tweet.read users.read offline.access',
    'state' => 'state',
    'code_challenge' => 'codeChallenge',
    'code_challenge_method' => 'S256'
  ];

  $url = $base_url . '?' . http_build_query($query);

  header('Location: ' . $url);

?>

callback.php

PHP
<?php
  session_start();

  define('Consumer_Key', 'Consumer Key');
  define('Consumer_Secret', 'Consumer Secret');
  define('Callback', 'http://127.0.0.1:3000/callback.php');
  define('Client_id', 'Client ID');
  define('Client_Secret', 'Client Secret');

  $base_url = 'https://api.twitter.com/2/oauth2/token';
  $user_creds = Consumer_Key.':'.Consumer_Secret;
  $client = Client_id.':'.Client_Secret;
  $authorization_code = $_GET['code'];

   $header = array(
    "Authorization: Basic " . $client,
    "Content-Type: application/x-ww-form-urlencoded",
  );

  $data = array(
    "grant_type" => "client_credentials",
    "client_id" => Client_id,
    "client_secret" => Client_Secret,
    "code" => $authorization_code,
    "redirect_uri" => Callback,
    "code_verifier" => "challenge",
  );

  $curl = curl_init();

  curl_setopt($curl, CURLOPT_URL, $base_url);
  curl_setopt($curl, CURLOPT_HTTPHEADER, $header);
  curl_setopt($curl, CURLOPT_POSTFIELDS, http_build_query($data));

  $response = curl_exec($curl);
  $result = json_decode($response, true);

  curl_close($curl);

  var_dump($result);

?>