eric6_browser does not start

Steps to reproduce:
1. Install Eric6 with `sudo apt-get install eric`
2. Launch `eric6_browser` from terminal

Expected results:
* eric6_browser started normally

Actual results:
* eric6_browser is not started, show the following output

```
$ eric6_browser
Warning: translation file 'qscintilla_en_US'could not be loaded.
Using default.
Traceback (most recent call last):
  File "/usr/share/eric/modules/eric6_browser.py", line 200, in <module>
    main()
  File "/usr/share/eric/modules/eric6_browser.py", line 192, in main
    res = Startup.simpleAppStartup(sys.argv,
  File "/usr/share/eric/modules/Toolbox/Startup.py", line 244, in simpleAppStartup
    w = mwFactory(argv)
  File "/usr/share/eric/modules/eric6_browser.py", line 129, in createMainWidget
    browser = WebBrowserWindow(home, '.', None, 'web_browser',
  File "/usr/share/eric/modules/WebBrowser/WebBrowserWindow.py", line 382, in __init__
    self.__tabWidget.newBrowser(QUrl.fromUserInput(home))
  File "/usr/share/eric/modules/WebBrowser/WebBrowserTabWidget.py", line 479, in newBrowser
    browser.setSource(QUrl(linkName))
  File "/usr/share/eric/modules/WebBrowser/WebBrowserView.py", line 314, in setSource
    self.load(name)
  File "/usr/share/eric/modules/WebBrowser/WebBrowserView.py", line 225, in load
    not self.__page.acceptNavigationRequest(
  File "/usr/share/eric/modules/WebBrowser/WebBrowserPage.py", line 136, in acceptNavigationRequest
    QWebEnginePage.NavigationTypeRedirect
AttributeError: type object 'QWebEnginePage' has no attribute 'NavigationTypeRedirect'

```

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: eric 20.2+ds1-1
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.10
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Sun Nov 1 12:06:03 2020
PackageArchitecture: all
SourcePackage: eric
UpgradeStatus: No upgrade log present (probably fresh install)