Fix: Register Divider block & added test cases 🐛

Author: KoditkarVedant

Src/Notion.Client/Models/Blocks/Block.cs

@@ -10,6 +10,7 @@ namespace Notion.Client
     [JsonSubtypes.KnownSubType(typeof(ChildPageBlock), BlockType.ChildPage)]
     [JsonSubtypes.KnownSubType(typeof(ChildDatabaseBlock), BlockType.ChildDatabase)]
     [JsonSubtypes.KnownSubType(typeof(CodeBlock), BlockType.Code)]
+    [JsonSubtypes.KnownSubType(typeof(DividerBlock), BlockType.Divider)]
     [JsonSubtypes.KnownSubType(typeof(EmbedBlock), BlockType.Embed)]
     [JsonSubtypes.KnownSubType(typeof(EquationBlock), BlockType.Equation)]
     [JsonSubtypes.KnownSubType(typeof(FileBlock), BlockType.File)]

Test/Notion.IntegrationTests/IBlocksClientTests.cs

@@ -239,6 +239,16 @@ private static IEnumerable<object[]> BlockData()
                         Assert.Equal("https://github.com/notion-dotnet/notion-sdk-net", updatedBlock.Bookmark.Url);
                         Assert.Equal("Github", updatedBlock.Bookmark.Caption.OfType<RichTextText>().First().Text.Content);
                     })
+                },
+                new object[] {
+                    new DividerBlock {
+                        Divider = new DividerBlock.Data()
+                    },
+                    new DividerUpdateBlock(),
+                    new Action<Block>((block) => {
+                        Assert.NotNull(block);
+                        Assert.IsType<DividerBlock>(block);
+                    })
                 }
             };
         }