Always keep your dependencies up to date. When you don’t upgrade, you miss out on bug fixes, security patches, and new features. You may even be up against an “end of life” deadline if the version of a package you use will soon no longer be supported.
If upgrading dependencies is so important, why don’t many developers do it? They may not know-how, or they may not understand the benefits of upgrading, or they may not feel like they have the time. Or, they may be afraid.