ubuntu20.04安装libgtk-3-dev一直报错如下：

Reading package lists... Done
Building dependency tree
Reading state information... Done
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:
 libgtk-3-dev : Depends: gir1.2-gtk-3.0 (= 3.24.18-1ubuntu1) but 3.24.20-0ubuntu1 is to be installed
                Depends: libatk-bridge2.0-dev but it is not going to be installed
                Depends: libgtk-3-0 (= 3.24.18-1ubuntu1) but 3.24.20-0ubuntu1 is to be installed
E: Unable to correct problems, you have held broken packages.

参考这篇文章的回答，执行如下操作：

/etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu focal-updates main
sudo apt update

后续就可以正常安装libgtk-3-dev了。