Please install python-git, python3-git, python-pathlib on Weblate VM

Originally created by @Anonymous on #15624 (Redmine)

We need these packages in order to solve tails/tails#15185.

We need the python3 version of this package mainly to make our scripts futureproof :)

Please reassign to me when done, thanks.

Parent Task: tails/sysadmin#11759

Edited May 15, 2020 by Anonymous