### Bug Description

Bold tag error

### How to Reproduce

html like this:
```

AppFlowyEditor

Bold tag

You can also use

AppFlowy Editor
```

``final html = htmlToDocument(htmlString);``
then print(html.toJson()):

``flutter: {document: {type: page, children: [{type: heading, data: {delta: [{insert: AppFlowyEditor}], level: 1}}, {type: paragraph, data: {delta: [{insert: Bold tag, attributes: {bold: true}}]}}, {type: paragraph, data: {delta: [{insert: You can also use}]}}, {type: paragraph, data: {delta: [{insert: Bold tag, attributes: {bold: true}}, {insert: AppFlowy Editor, attributes: {bold: true, italic: true}}]}}]}}``

### Expected Behavior

rt

### Operating System

iOS

### AppFlowy Editor Version(s)

Master

### Screenshots

_No response_

### Additional Context

_No response_