[bootstrap] replace packages not available on Ubuntu 20.04

[dsyx]

Use alternative packages:

$ sudo apt install bsdtar
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package bsdtar is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  libarchive-tools

E: Package 'bsdtar' has no installation candidate

[dsyx]

:thumbsup: LGTM