Repair the broken pip in python 3.8 venv against python 3.9 as system default

Suddenly distutils used for venv of python3.8 is disappeared after system updated.

In the look into /usr/lib/python3.8/distutils, many files are missing.

I found the workaround at https://askubuntu.com/questions/1239829/modulenotfounderror-no-module-named-distutils-util

My solution is that distutils in python3.8 has to be copied from distutils in python 3.9.

root@T480s:~# cp -r /usr/lib/python3.9/distutils /usr/lib/python3.8