Adaptions to Blender 3.0 API changes

Note:

This is still in beta and the behaviour may change between releases. Also bugs might still occur, which we'll try to fix as soon as possible. So feel free to report bugs and issues in the #w3d-blender-plugin channel on OpenSAGE Discord. Also see Troubleshoting for more information.

Changes:

• fixed issues with api changes in blender 3.0
• export texture names always with '.tga' extension