python-nautilus and python3-nautilus are in conflict on focal

Steps to reproduce:
1. Have Ubuntu 20.04 LTS installed
2. Try to install all nautilus stuff with

sudo apt-get install nautilus-*

Expected results:
* all packages are installed

Actual results:
* packages are not installed with

```
$ sudo apt-get install nautilus-*
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'nautilus-script-collection-svn' for glob 'nautilus-*'
Note, selecting 'nautilus-font-manager' for glob 'nautilus-*'
Note, selecting 'nautilus-script-debug' for glob 'nautilus-*'
Note, selecting 'nautilus-gtkhash' for glob 'nautilus-*'
Note, selecting 'nautilus-extension-burner' for glob 'nautilus-*'
Note, selecting 'nautilus-admin' for glob 'nautilus-*'
Note, selecting 'nautilus-owncloud' for glob 'nautilus-*'
Note, selecting 'nautilus-script-manager' for glob 'nautilus-*'
Note, selecting 'nautilus-dropbox' for glob 'nautilus-*'
Note, selecting 'nautilus-extension-gnome-terminal' for glob 'nautilus-*'
Note, selecting 'nautilus-extension-fma' for glob 'nautilus-*'
Note, selecting 'nautilus-share' for glob 'nautilus-*'
Note, selecting 'nautilus-wipe' for glob 'nautilus-*'
Note, selecting 'nautilus-sound-converter' for glob 'nautilus-*'
Note, selecting 'nautilus-sendto' for glob 'nautilus-*'
Note, selecting 'nautilus-filename-repairer' for glob 'nautilus-*'
Note, selecting 'nautilus-ideviceinfo' for glob 'nautilus-*'
Note, selecting 'nautilus-data' for glob 'nautilus-*'
Note, selecting 'nautilus-hide' for glob 'nautilus-*'
Note, selecting 'nautilus-extension-brasero' for glob 'nautilus-*'
Note, selecting 'nautilus-image-converter' for glob 'nautilus-*'
Note, selecting 'nautilus-script-audio-convert' for glob 'nautilus-*'
Note, selecting 'nautilus-actions' for glob 'nautilus-*'
Note, selecting 'nautilus-nextcloud' for glob 'nautilus-*'
Note, selecting 'nautilus-scripts-manager' for glob 'nautilus-*'
nautilus-admin is already the newest version (1.1.9-3).
nautilus-data is already the newest version (1:3.36.2-0ubuntu1).
nautilus-data set to manually installed.
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nautilus-owncloud : Depends: python-nautilus but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

```

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: nautilus-owncloud (not installed)
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Uname: Linux 5.4.0-26-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Fri May 15 19:04:33 2020
InstallationDate: Installed on 2020-04-23 (21 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: owncloud-client
UpgradeStatus: No upgrade log present (probably fresh install)