Urdf Robot Editor script keeps enabling Use Gravity and Convex Colliders after every Play

[megatran]

Describe the bug

Urdf Robot Editor script keeps enabling Use Gravity and Convex` after every Play.

To Reproduce
Steps to reproduce the behavior:

1. Get URDF Importer 0.5.2-preview
2. Import robot from select URDF file
3. Disable Use Gravity and Convex
   
4. Click "Play" in Unity to enter play mode
5. Stop play mode
6. Now these two settings are automatically enabled again....
   

Expected behavior
Once these two settings are disabled, they should remain disabled...

Environment (please complete the following information, where applicable):

• Unity Version: [Unity 2020.3.28f1, 2020.3.37f1]
• Unity machine OS + version: [e.g. Windows 10]
• ROS machine OS + version: [e.g. ROS Noetic]
• ROS–Unity communication: [Unity TCP Endpoint]