Unable to install Deja-Dup from MATE Welcome (Optional Tasks tab)

[Norbert]

Steps to reproduce:
1. Install Ubuntu MATE 19.04
2. Launch MATE Welcome
3. Go to Optional Tasks
4. Click install on Backups - Deja Dup - Install

Expected results:
* Deja Dup got installed

Actual results:
* Deja Dup does not install with the following error message:

   Package does not exist
   Check the spelling of the package name, and that the appropriate repository is enabled.
   Details
        Package deja-dup-backend-cloudfiles isn't available

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: ubuntu-mate-welcome (not installed)
ProcVersionSignature: Ubuntu 4.18.0-11.12-generic 4.18.12
Uname: Linux 4.18.0-11-generic x86_64
ApportVersion: 2.20.10-0ubuntu19
Architecture: amd64
Date: Mon Jan 28 13:02:51 2019
InstallationDate: Installed on 2019-01-28 (0 days ago)
InstallationMedia: Ubuntu-MATE 19.04 "Disco Dingo" - Alpha amd64 (20190128)
SourcePackage: ubuntu-mate-welcome
UpgradeStatus: No upgrade log present (probably fresh install)

[Norbert (nrbrtx)]

Confirmed on beta2 of Ubuntu MATE 19.04.
The `apt-get update` was ran before.