Duration for gifted subs

[10011000100000]

Is your feature request related to a problem? Please describe.
Not really a problem, I just thought it'd be nice to have info about sub duration on gifted subs as well, not just new and renewed ones

Describe the solution you'd like
Add duration property to giftees in channel.subscription.gifts event
e.g.,

"giftees": 
[
  {
    "is_anonymous": false,
    "user_id": 561654654,
    "username": "giftee_name",
    "is_verified": true,
    "profile_picture": "https://example.com/broadcaster_avatar.jpg",
    "channel_slug": "giftee_channel",
    "identity": null,
    "duration": 3
  },
],