Version 6 is not compatible with Angular 10 and Ivy

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Current behavior
Version 6 is not compatible with Angular 10 (Ivy compatibility issues).

Expected behavior
Version 6 minor release/patch to be Ivy-compatible without breaking changes introduced in subsequent releasess till 8.1.2.

Reproduction of the problem

What is the motivation / use case for changing the behavior?
ngx-dnd is a dependency of another dependency in my project, so it is impossible to just update the package.
As I can see, there must not be too much changes from 6 to 8.1.2 (first Ivy-compatible release) to make the 6 version simply compatible with Ivy and Angular 10 without any other features / breaking changes introduced.

Please tell us about your environment:

• ngx-dnd version: 6.0.0
  I'm interested in this particular major 6 version.

• Angular version: 6.1.1
  I'm aiming at upgrading from Angular 6.1.1 to 10.

• Browser: [all | Chrome XX | Firefox XX | IE XX | Safari XX | Mobile Chrome XX | Android X.X Web Browser | iOS XX Safari | iOS XX UIWebView | iOS XX WKWebView ]
  all

• Language: [all | TypeScript X.X | ES6/7 | ES5]
  all