const operations = [
  { date: "2017-07-31", amount: "5422" },
  { date: "2017-06-30", amount: "5220" },
  { date: "2017-05-31", amount: "5365" },
  { date: "2017-08-31", amount: "5451" },
  { date: "2017-09-30", amount: "5303" },
  { date: "2018-03-31", amount: "5654" },
  { date: "2017-10-31", amount: "5509" },
  { date: "2017-12-31", amount: "5567" },
  { date: "2018-01-31", amount: "5597" },
  { date: "2017-11-30", amount: "5359" },
  { date: "2018-02-28", amount: "5082" },
  { date: "2018-04-14", amount: "2567" },
];

// Задача: преобразовать данный массив в объект следующего вида:
// {
//   '2017': ['05-31', '06-30', '07-31', '08-31', '09-30', '10-31', '11-30', '12-31'],
//   '2018': ['01-31', '02-28', '03-31', '04-14']
// }