最近我将 Ubuntu 安装从 18.04 升级到 20.04.1，但升级后 LibreOffice 默认不可用。当我尝试通过运行以下命令进行安装时：
sudo apt install libreoffice libreoffice-gtk
我收到此错误：
The following packages have unmet dependencies:
libreoffice :
**Depends: python3-uno (>= 4.4.0~beta2) but it is not going to be installed**
**Recommends: libreoffice-script-provider-python but it is not
going to be installed**
E: Unable to correct problems, you have held
broken packages.
我尝试修复损坏的软件包并尝试了在 Stack Overflow 上找到的各种解决方案，但对我没有任何作用。
到目前为止我已经尝试过：
方法一：
$ sudo apt install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 8 not upgraded.
方法2：
sudo apt update
sudo apt upgrade
方式三：
cat /etc/apt/sources.list
# deb cdrom:[Ubuntu 18.04.1 LTS _Bionic Beaver_ - Release amd64 (20180725)]/ bionic main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ focal main restricted
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ focal-updates main restricted
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ focal universe
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic universe
deb http://us.archive.ubuntu.com/ubuntu/ focal-updates universe
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ focal multiverse
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://us.archive.ubuntu.com/ubuntu/ focal-updates multiverse
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
# deb-src http://bd.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner
deb http://us.archive.ubuntu.com/ubuntu/ focal-security main restricted
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://us.archive.ubuntu.com/ubuntu/ focal-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://us.archive.ubuntu.com/ubuntu/ focal-security multiverse
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse
# deb [arch=amd64] https://download.docker.com/linux/ubuntu focal stable # disabled on upgrade to focal
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable
# deb-src [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable
我现在能做什么？