### 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)

{
		Light *light = p_lights;
		while (light) {
			if (light->render_index_cache >= 0 && p_item->light_mask & light->item_mask && p_item->z_final >= light->z_min && p_item->z_final <= light->z_max && p_item->global_rect_cache.intersects_transformed(light->xform_cache, light->rect_cache)) {
				uint32_t light_index = light->render_index_cache;
				lights[light_count >> 2] |= light_index << ((light_count & 3) * 8);
				light_count++;
				if (light_count == data.max_lights_per_item - 1) {
					break;
				}
			}
			light = light->next_ptr;
		}
		base_flags |= light_count << FLAGS_LIGHT_COUNT_SHIFT;
	}
	bool lights_disabled = light_count == 0 && !state.using_directional_lights;
	if (lights_disabled != state.canvas_instance_batches[state.current_batch_index].lights_disabled) {
		_new_batch(r_batch_broken);
		state.canvas_instance_batches[state.current_batch_index].lights_disabled = lights_disabled;
	}
	const Item::Command *c = p_item->commands;
	while (c) {
		if (skipping && c->type != Item::Command::TYPE_ANIMATION_SLICE) {
			c = c->next;
			continue;
		}
		if (c->type != Item::Command::TYPE_MESH) {
			
			_update_transform_2d_to_mat2x3(base_transform * draw_transform, state.instance_data_array[r_index].world);
		}