could not able to create contact using php api #344

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Version info

• intercom-php version: 4.4.3
• Intercom API version: 2.3
• PHP version: 7.3

Expected behavior

Able to create contact using intercom php api

Actual behavior

 try to create contact using 
   $client->contacts->create([
      'email' => 'test@example.com',
      'external_id' => '2022'
  ]);
  But get an error response   "Conflict"
  While checking intercom account . there is not exising contact with user_id with 2022 and email
  But not happened in all request.
 Able to create this contact using intercom panel

Steps to reproduce (as granular as possible, including screenshots where appropriate)

1. Create a contact via API
2. Addidng credential external_id