Add interface for Wiki database

Author: KoditkarVedant

Src/Notion.Client/Models/Database/Database.cs

@@ -4,7 +4,7 @@
 
 namespace Notion.Client
 {
-    public class Database : IObject, IObjectModificationData
+    public class Database : IObject, IObjectModificationData, IWikiDatabase
     {
         [JsonProperty("title")]
         public List<RichTextBase> Title { get; set; }

Src/Notion.Client/Models/Database/IWikiDatabase.cs

@@ -0,0 +1,13 @@
+using JsonSubTypes;
+using Newtonsoft.Json;
+
+namespace Notion.Client
+{
+    [JsonConverter(typeof(JsonSubtypes), "object")]
+    [JsonSubtypes.KnownSubTypeAttribute(typeof(Page), ObjectType.Page)]
+    [JsonSubtypes.KnownSubTypeAttribute(typeof(Database), ObjectType.Database)]
+    public interface IWikiDatabase : IObject
+    {
+
+    }
+}

Src/Notion.Client/Models/Page/Page.cs

@@ -4,7 +4,7 @@
 
 namespace Notion.Client
 {
-    public class Page : IObject, IObjectModificationData
+    public class Page : IObject, IObjectModificationData, IWikiDatabase
     {
         /// <summary>
         ///     The parent of this page. Can be a database, page, or workspace.