Merge pull request #1055 from DLR-RM/iss1054_scene_pop_cleanup

fix(init): Fixes cleanup of scene properties

blenderproc/python/utility/Initializer.py

@@ -162,5 +162,5 @@ def remove_all_data(remove_camera: bool = True):
     @staticmethod
     def remove_custom_properties():
         """ Remove all custom properties registered at global entities like the scene. """
-        for key in bpy.context.scene.keys():
+        for key in list(bpy.context.scene.keys()):
             del bpy.context.scene[key]