Allow strings in date range aggregation

[pquentin]

Should fix the following test:

// Test file: /test/free/aggregations/range.yml
// Test name: Range aggregation on date field

import { expectAssignable } from 'tsd'
import * as T from '../types'

expectAssignable<T.SearchRequest>({
  "body": {
    "aggs": {
      "date_range": {
        "range": {
          "field": "date",
          "ranges": [
            {
              "from": "2021-05-01T00:00:00Z",
              "to": "2021-05-05T00:00:00Z"
            }
          ]
        }
      }
    },
    "size": 0
  },
  "index": "date_range_test",
  "typed_keys": true
})

[github-actions]

Following you can find the validation changes against the target branch for the API.

API	Status	Request	Response
search	🔴	2540/2602 → 2541/2602	2602/2602

You can validate this API yourself by using the make validate target.