使用环境：Ubuntu 20.04版
在终端中运行sudo apt-get install libxml2-dev。但返回以下消息：

Reading package lists... Done
Building dependency tree... Done
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:
 libxml2-dev : Depends: libxml2 (= 2.9.10+dfsg-6.3ubuntu0.1) but 2.9.12+dfsg-0+ubuntu21.04.1+deb.sury.org+1 is to be installed
E: Unable to correct problems, you have held broken packages.

libxml2-dev : Depends: libxml2 (= 2.9.10+dfsg-6.3ubuntu0.1) but 2.9.12+dfsg-0+ubuntu21.04.1+deb.sury.org+1 is to be installed是什么意思？我该怎么解决它？
谢谢你！