### 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)

}
		switch (c->type) {
			case Item::Command::TYPE_RECT: {
				const Item::CommandRect *rect = static_cast<const Item::CommandRect *>(c);
				if (rect->flags & CANVAS_RECT_TILE && state.canvas_instance_batches[state.current_batch_index].repeat != RenderingServer::CanvasItemTextureRepeat::CANVAS_ITEM_TEXTURE_REPEAT_ENABLED) {
					_new_batch(r_batch_broken);
					state.canvas_instance_batches[state.current_batch_index].repeat = RenderingServer::CanvasItemTextureRepeat::CANVAS_ITEM_TEXTURE_REPEAT_ENABLED;
				}
				if (rect->texture != state.canvas_instance_batches[state.current_batch_index].tex || state.canvas_instance_batches[state.current_batch_index].command_type != Item::Command::TYPE_RECT) {
					_new_batch(r_batch_broken);
					state.canvas_instance_batches[state.current_batch_index].tex = rect->texture;
					state.canvas_instance_batches[state.current_batch_index].command_type = Item::Command::TYPE_RECT;
					state.canvas_instance_batches[state.current_batch_index].command = c;
					state.canvas_instance_batches[state.current_batch_index].shader_variant = CanvasShaderGLES3::MODE_QUAD;
				}
				_prepare_canvas_texture(rect->texture, state.canvas_instance_batches[state.current_batch_index].filter, state.canvas_instance_batches[state.current_batch_index].repeat, r_index, texpixel_size);
				Rect2 src_rect;
				Rect2 dst_rect;
				if (rect->texture != RID()) {
					src_rect = (rect->flags & CANVAS_RECT_REGION) ? Rect2(rect->source.position * texpixel_size, rect->source.size * texpixel_size) : Rect2(0, 0, 1, 1);
					dst_rect = Rect2(rect->rect.position, rect->rect.size);
					if (dst_rect.size.width < 0) {
						dst_rect.position.x += dst_rect.size.width;
						dst_rect.size.width *= -1;
					}
					if (dst_rect.size.height < 0) {
						dst_rect.position.y += dst_rect.size.height;
						dst_rect.size.height *= -1;
					}
					if (rect->flags & CANVAS_RECT_FLIP_H) {