Grant type not supported error in Salesforce

I am using Sales Force Oauth API. I am using PHP and Curl for API Integration. When I hit API using Post Method, I am getting this error message unsupported grant type.

When I hit the same API using the Postman with the same headers and body I'm getting desired response. But getting an error on my webpage. Below is the code. Thanks for the help.

<?php 

$url = 'https://mycompanynamegoeshere.my.salesforce.com/services/oauth2/token';
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_POST, true);

$data = [
    'grant_type' => 'client_credentials',
    'client_id' => 'client id goes here',
    'client_secret' => 'client secret goes here',
];

$data_json = json_encode($data);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_json);

curl_setopt(
    $ch,
    CURLOPT_HTTPHEADER,
    array(
        'Content-Type: application/x-www-form-urlencoded',
        'Content-Length: ' . strlen($data_json),
        'Cache-Control: no-cache',
        'Connection: keep-alive',
        'Accept: application/json',
    ),
);

$response = curl_exec($ch);
curl_close($ch);
echo $response;

?>

Below is the error message

{"error":"unsupported_grant_type","error_description":"grant type not supported"}1

I tried many online solutions. But not getting any output. API works fine in Postman and getting below output:

{
    "access_token": "access token comes here",
    "signature": "signature comes here",
    "scope": "scope id comes here",
    "instance_url": "my company salesforce url comes here",
    "id": "my company id",
    "token_type": "token comes here",
    "issued_at": "issue comes here"
}

<?php

$curl = curl_init();

curl_setopt_array(
    $curl,
    array(
        CURLOPT_URL => 'https://companyname.my.salesforce.com/services/oauth2/token',
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_ENCODING => '',
        CURLOPT_MAXREDIRS => 10,
        CURLOPT_TIMEOUT => 0,
        CURLOPT_FOLLOWLOCATION => true,
        CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
        CURLOPT_CUSTOMREQUEST => 'POST',
        CURLOPT_POSTFIELDS => 'grant_type=client_credentials&client_id=client_id_goes_here&client_secret=client_secret_goes_here',
        CURLOPT_HTTPHEADER => array(
            'Content-Type: application/x-www-form-urlencoded',
            'Accept: application/json',
            'Cookie: BrowserId=browser_id_goes_here; CookieConsentPolicy=0:1; LSKey-c$CookieConsentPolicy=0:1'
        ),
    )
);

$response = curl_exec($curl);
$decoded = json_decode($response, true);
$accessToken = $decoded["access_token"];
curl_close($curl);

?>