Importer/Exporter: uv coordinates flipped when importing exported scene.

[DoeringChristian]

Bug Description
When exporting a scene to the mitsuba format and importing it back into blender the vertical axis of the uv map is flipped.

To Reproduce
Steps to reproduce the behavior:

1. Export scene to mitsuba xml
2. Import same scene to blender

Expected behavior
UV coordinates should be the same after importing

Resources
Before:

After:

Environment:

• OS: Linux
• Blender Version: 3.3
• Add-on Version: latest

[ros-dorian]

Hello,

Good catch! This PR should fix this problem, but I'll let you double-check that it indeed works now.

Cheers!