[bug report] @types/dragula is using old 2.x

REQUIRED: Before filing a bug report

Change each [ ] to [x] when you have done it.

[x] My issue title starts with [bug report]
[x] I have read the README, especially the 'classic blunders' section, and the dragula docs.
[x] I have searched through the ng2-dragula issues for related problems, including closed issues.
[x] I have browsed through the issues labeled "future reference" for problems that have been solved before or have a known workaround.
[x] I am using the latest version of ng2-dragula.

Describe the bug (required)

The peer dependency for latest ng2-dragula is using an old @types/dragula (i.e. 2x)

To Reproduce (required)

Look in package.json and you see:

  "peerDependencies": {
    "@types/dragula": "^2.1.34",
    "dragula": "^3.7.2",

Screenshots (optional)

If applicable, add screenshots to help explain your problem.

Versions (required)

Please state which versions of the following packages you have installed:

  "name": "ng2-dragula",
  "private": false,
  "version": "5.1.0",

Browsers affected (optional)

Is this a bug in a particular browser? If so, it's unlikely that it's a problem with ng2-dragula. Instead, it is probably a bug in dragula.

Additional context (optional)

Add any other context about the problem here.

valor-software / ng2-dragula