Removing DER as a dependency breaks websites

Problem/Motivation

Upgrading from 2.0.0 to 2.0.2 causes site to white screen on saving content and causes drush updb to error.

I suspect this is due to removing the requirement on Dynamic Entity Reference without providing an update hook to uninstall it first.

Steps to reproduce

1. Upgrade module from 2.0.0 to 2.0.2
2. Run drush updb - will fail
3. Attempt to save content - site white screens

Proposed resolution

Re-add Dynamic Entity Reference as a dependency and provide a proper update hook to uninstall the module before removing it entirely.

This will absolutely cause issues going from 2.0.x to 2.1.x as well assuming there's no update hook to uninstall the dependency.