### 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.current_instance_buffer_index++;
	if (int(state.current_instance_buffer_index) < state.canvas_instance_data_buffers[state.current_data_buffer_index].instance_buffers.size()) {
		
		return;
	}
	GLuint new_buffer;
	glGenBuffers(1, &new_buffer);
	glBindBuffer(GL_ARRAY_BUFFER, new_buffer);
	glBufferData(GL_ARRAY_BUFFER, data.max_instance_buffer_size, nullptr, GL_STREAM_DRAW);
	state.canvas_instance_data_buffers[state.current_data_buffer_index].instance_buffers.push_back(new_buffer);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
}
void RasterizerCanvasGLES3::set_time(double p_time) {
	state.time = p_time;
}
RasterizerCanvasGLES3 *RasterizerCanvasGLES3::singleton = nullptr;
RasterizerCanvasGLES3 *RasterizerCanvasGLES3::get_singleton() {
	return singleton;
}
RasterizerCanvasGLES3::RasterizerCanvasGLES3() {
	singleton = this;
	GLES3::TextureStorage *texture_storage = GLES3::TextureStorage::get_singleton();
	GLES3::MaterialStorage *material_storage = GLES3::MaterialStorage::get_singleton();
	GLES3::Config *config = GLES3::Config::get_singleton();
	polygon_buffers.last_id = 1;
	
	{
		glGenBuffers(1, &data.canvas_quad_vertices);
		glBindBuffer(GL_ARRAY_BUFFER, data.canvas_quad_vertices);
		const float qv[8] = {