21230: Remove pip install from get-package-version

21230: Remove pip install from get-package-version

Reasons to remove this: it can't work on Debian 12+, and the code has
obviously gotten stale with its original rationale ('setuptools<45' is
definitely not "latest setuptools").

Nobody can tell me what context this runs in. I'm going to hope that it
runs in some context where setuptools is already available. If it turns
out I'm wrong, then hopefully that will break the build in a way that
lets me assess our options.

Arvados-DCO-1.1-Signed-off-by: Brett Smith <brett.smith@curii.com>