Unable to use Anki on Ubuntu 18.10

[Norbert]

Steps to reproduce:
1. Install Anki on Ubuntu 18.10 with `sudo apt install anki`
2. Run Anki from terminal with `anki`

Expected results:
* Anki starts normally

Actual results:
* Anki does not start, show the following messages on start:

1. Window named "Qt version issue"

> You are using Qt version 5.11.1. Anki has only been tested upstream with version Qt 5.9.x. Upstream suggests only using version Qt 5.9.x, and a standalone version containing the required libraries can be downloaded from the Anki website. Continuing with this Debian version could potentially lead to loss of data (though this is unlikely). Are you sure you want to continue?

2. Aftrer clicking yes it shows window named Anki:

> Error during startup:
Traceback (most recent call last):
  File "/usr/share/anki/aqt/main.py", line 50, in __init__
    self.setupUI()
  File "/usr/share/anki/aqt/main.py", line 75, in setupUI
    self.setupMainWindow()
  File "/usr/share/anki/aqt/main.py", line 585, in setupMainWindow
    tweb = self.toolbarWeb = aqt.webview.AnkiWebView()
  File "/usr/share/anki/aqt/webview.py", line 114, in __init__
    self.focusProxy().installEventFilter(self)
AttributeError: 'NoneType' object has no attribute 'installEventFilter'

Clicking OK here does not show GUI.

Note: the problem was seen on AskUbuntu ( https://askubuntu.com/q/1123867/66509 )

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: anki 2.1.0+dfsg-1
ProcVersionSignature: Ubuntu 4.18.0-15.16-generic 4.18.20
Uname: Linux 4.18.0-15-generic x86_64
ApportVersion: 2.20.10-0ubuntu13.2
Architecture: amd64
CurrentDesktop: MATE
Date: Thu Mar 7 23:33:30 2019
InstallationDate: Installed on 2019-02-17 (18 days ago)
InstallationMedia: Ubuntu-MATE 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.2)
PackageArchitecture: all
SourcePackage: anki
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.