refactor: correct data type on confirmation and validation

[amosmachora]

This PR fixes the endpoints safaricom hits with correct responses to avoid failing requests as we wait for @Injiri to configure the validtion and confirmation URLs

[Murithijoshua]

LGTM

[Injiri]

@amosmachora let me put this here for reference
setup is as below for the respective parameters for Buy Goods integration for Lipa Na M-PESA/STKPUSH

{ 
  BusinessShortcode – short code used during Go Live
  PartyB – Till Number (where customers usually pay to) 
  TransactionType – CustomerBuyGoodsOnline.
}

[ojwanganto]

Thanks, @Injiri