### 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)

}
	
	uint32_t light_count = 0;
	uint32_t directional_light_count = 0;
	{
		Light *l = p_directional_light_list;
		uint32_t index = 0;
		while (l) {
			if (index == data.max_lights_per_render) {
				l->render_index_cache = -1;
				l = l->next_ptr;
				continue;
			}
			CanvasLight *clight = canvas_light_owner.get_or_null(l->light_internal);
			if (!clight) { 
				l->render_index_cache = -1;
				l = l->next_ptr;
				ERR_CONTINUE(!clight);
			}
			Vector2 canvas_light_dir = l->xform_cache.columns[1].normalized();
			state.light_uniforms[index].position[0] = -canvas_light_dir.x;
			state.light_uniforms[index].position[1] = -canvas_light_dir.y;
			_update_transform_2d_to_mat2x4(clight->shadow.directional_xform, state.light_uniforms[index].shadow_matrix);
			state.light_uniforms[index].height = l->height; 
			for (int i = 0; i < 4; i++) {
				state.light_uniforms[index].shadow_color[i] = uint8_t(CLAMP(int32_t(l->shadow_color[i] * 255.0), 0, 255));
				state.light_uniforms[index].color[i] = l->color[i];
			}
			state.light_uniforms[index].color[3] = l->energy; 
			if (state.shadow_fb != 0) {