Add support for Divider block type

[KoditkarVedant]

Notion has added support for adding and retrieving Divider block types.

Divider blocks
You can now can add Divider blocks to pages and other blocks.

Below is an example response from Append block children containing a Divider block uploaded to Notion.

{
    "object": "list",
    "results": [
        {
            "object": "block",
            "id": "block-id",
            "created_time": "2021-10-14T18:10:00.000Z",
            "last_edited_time": "2021-10-14T18:10:00.000Z",
            "has_children": false,
            "archived": false,
            "type": "divider",
            "divider": {}
        }
    ],
    "next_cursor": null,
    "has_more": false
}

Notion API change log: https://developers.notion.com/changelog/table-of-contents-and-divider-block-types-are-now-supported