connect calls recordings and WATI chats to contacts on hubspot

I am trying to upload call recordings on hubspot and create association to the related contacts using rails but getting errors.

Here is the script:

api_url = “https://api.hubapi.com/crm/v3/objects/calls

url = recording_url

body = {

“properties”: {

"hs\_timestamp": "2021-03-17T01:32:44.872Z",

"hs\_call\_title": "Discovery call",

"hubspot\_owner\_id": "11349275740",

"hs\_call\_body": " testing",

"hs\_call\_from\_number": "23194159",

"hs\_call\_to\_number": "25302229",

"hs\_call\_recording\_url": url,

"hs\_call\_status": "COMPLETED"

},

“associations”: [

{

  "to": {

    "id": 179552

  },

  "types": \[

    {

      "associationCategory": "HUBSPOT\_DEFINED",

      "associationTypeId": 193

    }

  ]

}

]

}

response = RestClient.post(api_url, body, headers: {‘Content-Type’ => ‘application/json’,‘Authorization’=> “Bearer #{ENV[‘HUBSPOT_ACCESS_TOKEN’]}” })
and with abive script I am getting followign error:
RestClient::UnsupportedMediaType: 415 Unsupported Media Type