18.04 – How to get source version of containerd 1.3.3 via apt?

Package containerd in version 1.3.3 seems to be the most recent one for Ubuntu Bionic architecture amd64:

$ apt show containerd      
Package: containerd
Version: 1.3.3-0ubuntu1~18.04.4
Priority: optional
...

Unfortunately the sources are not available.

$ apt-get source containerd      
Reading package lists... Done
E: Unable to find a source package for containerd


$ cat /etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu/ bionic main restricted
deb-src http://archive.ubuntu.com/ubuntu/ bionic main restricted
deb http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted

It seems like the sources are only available for the most recent version. Which is 1.4.4. But this version is not available for amd64.

Is there a way of getting the sources for the recent containerd version 1.3.3 via apt ?