update Africa's Talking channel

[manumoreira]

Testing a channel recently we realized that verboice code is not handling the case calSessionState = "Answered"

We are receiving this first request:

{
  "callSessionState": "Answered",
  "sessionId": "ATVId_11163e2ea9a58f3a7999fecda8eeb43a",
  "callerCountryCode": "256",
  "callerCarrierName": "Airtel",
  "isActive": "1",
  "callStartTime": "2021-10-13+19:10:16",
  "direction": "Outbound",
  "destinationNumber": "+2563XXXX0647",
  "callerNumber": "+2567XXXX9081"
}

And we are answering OKinstead of sending the first step of the flow

[matiasgarciaisaia]

Fixed in #895