text: Title: [BUG] label with angle brackets <> causes display errors
  Body: **Describe the bug**
  When the label contains **<>**, the label list will show, for example `<NONCAR><font color="#c8c8c8"> 〇 </font>`. Meanwhile, in the _polygon labels_ panel, only the color circle shows but not the name <NONCAR>.
  
  **To Reproduce**
  Steps to reproduce the behavior:
  1. create a polygon and label it as **<text>**
  
  **Expected behavior**
  like other normal labels
  
  **Desktop:**
   - OS: MacOS 10.15.4
   - Labelme Version 4.2.10
  
  
  