pyrender: Failed rendering frame


These steps resolved the rendering issue for me:

1. Set the environment variable:

   ```bash
   setenv PYOPENGL_PLATFORM egl
   ```

2. Upgrade PyOpenGL and PyOpenGL\_accelerate:

   ```bash
   pip install --upgrade PyOpenGL PyOpenGL_accelerate
   ```

3. In `demo.py`, make sure to set the environment variable in code:

   ```python
   import os
   os.environ['PYOPENGL_PLATFORM'] = 'egl'
   ```
