graphics: drop model_buf after upload

src/graphics.rs

@@ -26,7 +26,6 @@ impl Indices{
 }
 struct GraphicsModel{
 	indices:Indices,
-	model_buf:wgpu::Buffer,
 	vertex_buf:wgpu::Buffer,
 	bind_group:wgpu::BindGroup,
 	instance_count:u32,
@@ -501,7 +500,6 @@ impl GraphicsState{
 						model_graphics::Indices::U16(indices)=>Indices::new(device,indices,wgpu::IndexFormat::Uint16),
 					},
 					bind_group,
-					model_buf,
 				});
 			}
 		}