### 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)

GLES3::TextureStorage *texture_storage = GLES3::TextureStorage::get_singleton();
	GLES3::MaterialStorage *material_storage = GLES3::MaterialStorage::get_singleton();
	GLES3::MeshStorage *mesh_storage = GLES3::MeshStorage::get_singleton();
	Transform2D canvas_transform_inverse = p_canvas_transform.affine_inverse();
	
	reset_canvas();
	if (state.canvas_instance_data_buffers[state.current_data_buffer_index].fence != GLsync()) {
		GLint syncStatus;
		glGetSynciv(state.canvas_instance_data_buffers[state.current_data_buffer_index].fence, GL_SYNC_STATUS, sizeof(GLint), nullptr, &syncStatus);
		if (syncStatus == GL_UNSIGNALED) {
			
			if (state.canvas_instance_data_buffers[state.current_data_buffer_index].last_frame_used < RSG::rasterizer->get_frame_number() - 2) {
#ifndef WEB_ENABLED
				
				glClientWaitSync(state.canvas_instance_data_buffers[state.current_data_buffer_index].fence, 0, 100000000); 
#endif
				state.canvas_instance_data_buffers[state.current_data_buffer_index].last_frame_used = RSG::rasterizer->get_frame_number();
				glDeleteSync(state.canvas_instance_data_buffers[state.current_data_buffer_index].fence);
				state.canvas_instance_data_buffers[state.current_data_buffer_index].fence = GLsync();
			} else {
				
				
				_allocate_instance_data_buffer();
			}
		} else {
			
			state.canvas_instance_data_buffers[state.current_data_buffer_index].last_frame_used = RSG::rasterizer->get_frame_number();
			glDeleteSync(state.canvas_instance_data_buffers[state.current_data_buffer_index].fence);
			state.canvas_instance_data_buffers[state.current_data_buffer_index].fence = GLsync();
		}