Error of "minimum-stability (stable)" during install with composer.

Problem/Motivation

Getting error as -

 [InvalidArgumentException]                                                                                                                                                        
Could not find a version of package drupal/cl_generator matching your minimum-stability (stable). Require it with an explicit version constraint allowing its desired stability.

I have tried adding "minimum-stability": "stable" in composer.json but this is not working.

Steps to reproduce

try to install with composer as composer require 'drupal/cl_generator:^2.0.0-beta1'