Get public XUMM statistics

To get public statistics about the amount of active XUMM users & the version they are using, JSON is served at:
https://xumm.app/api/v1/internal/stats/public

We have no statistics (as we store as little info as possible) on the amount of on ledger accounts managed with XUMM; these numbers are unique devices, used to open XUMM at least once in the past three months.

Unique users may be counted double if they abandoned their phone or reinstalled XUMM in the past three months. Unique users may not be counted if they "set and forget" to hold, and only open XUMM occasionally (if they want to send a transaction), and didn't in the past three months.

Sample output (Aug. 7, 2021):

{
  "activated_devices": 160360,
  "active_last_24h": 7083,
  "versions": {
    "2.0.2": 55022,
    "1.0.1": 34093,
    "2.1.1": 26711,
    "0.6.0": 16457,
    "0.5.1": 9342,
    "0.5.2": 4553,
    "0.5.0": 3383,
    "0.2.4": 3242,
    "2.0.1": 2059,
    "0.4.1": 1924,
    "0.3.0": 1790,
    "2.1.0": 624,
    "2.0.0": 580,
    "2.1.2": 383,
    "1.0.0": 109
  }
}