Add support for verification page property

[KoditkarVedant]

The verification page property was added to the Page properties

Example verification page property values as returned in a GET page request

Unverified

{
  Verification: {
    id: "fpVq",
    type: "verification",
    verification: { state: "unverified", verified_by: null, date: null },
  },
}

Verified with no expiration date set

{
  Verification: {
    id: "fpVq",
    type: "verification",
    verification: {
      state: "verified",
      verified_by: {
        object: "user",
        id: "01e46064-d5fb-4444-8ecc-ad47d076f804",
        name: "User Name",
        avatar_url: null,
        type: "person",
        person: {},
      },
      date: { start: "2023-08-01T04:00:00.000Z", end: null, time_zone: null },
    },
  },
}

Verified with 90-day expiration date

{
  Verification: {
    id: "fpVq",
    type: "verification",
    verification: {...},
      date: {
        start: "2023-08-01T04:00:00.000Z",
        end: "2023-10-30T04:00:00.000Z",
        time_zone: null,
      },
    },
  },
}

Notion Change log: https://developers.notion.com/page/changelog#july-25---august-7-2023

[KoditkarVedant]

#368