Send mail in laravel by using klaviyo but got 'error (403) You must specify an API key to make requests.'

Question

public function forgetPassword(Request $request){
  try{  
                       $klaviyoResponse = Http::withHeaders([
                            'Authorization' => 'Bearer ' . $klaviyoApiKey,
                            'Content-Type' => 'application/json',
                        ])->post('https://a.klaviyo.com/api/v1/email-template/send', [
                            'email' => $recipientEmail,
                            'template_id' => $templateId,
                            'context' => [
                                'reset_link' => $resetLink,
                                'token' => $token
                            ],
                        ]); 
    }catch(Exception $e){
                return response()->json(['status'=>false,'message' =>$e->getMessage()],400);
            }
        }

Error: array:2 [ "status" => 403 "message" => "You must specify an API key to make requests." ]

Help me to solve this Forbidden error i also follow the klaviyo documentation but still stucked.