### Godot version

4.0 beta 17

### System information

Windows 10

### Issue description

Setting the color attribute in ParticleProcessMaterial for GPUParticles2D does not work with compatibility renderer
(works with forward+)

### Steps to reproduce

Set renderer to compatibility
Create a GPUParticles2D
Add ParticleProcessMaterial and set Color attribute (creating a particle shader and setting the `COLOR` is the same)


### Minimal reproduction project

[Particle2DColor.zip](https://github.com/godotengine/godot/files/10678236/Particle2DColor.zip)

state.instance_data_array[r_index].src_rect[j] = 0;
					state.instance_data_array[r_index].dst_rect[j] = 0;
					state.instance_data_array[r_index].ninepatch_margins[j] = 0;
				}
				_add_to_batch(r_index, r_batch_broken);
			} break;
			case Item::Command::TYPE_TRANSFORM: {
				const Item::CommandTransform *transform = static_cast<const Item::CommandTransform *>(c);
				draw_transform = transform->xform;
			} break;
			case Item::Command::TYPE_CLIP_IGNORE: {
				const Item::CommandClipIgnore *ci = static_cast<const Item::CommandClipIgnore *>(c);
				if (current_clip) {
					if (ci->ignore != reclip) {
						_new_batch(r_batch_broken);
						if (ci->ignore) {
							state.canvas_instance_batches[state.current_batch_index].clip = nullptr;
							reclip = true;
						} else {
							state.canvas_instance_batches[state.current_batch_index].clip = current_clip;
							reclip = false;
						}
					}
				}
			} break;
			case Item::Command::TYPE_ANIMATION_SLICE: {
				const Item::CommandAnimationSlice *as = static_cast<const Item::CommandAnimationSlice *>(c);
				double current_time = RSG::rasterizer->get_total_time();
				double local_time = Math::fposmod(current_time - as->offset, as->animation_length);
				skipping = !(local_time >= as->slice_begin && local_time < as->slice_end);