Untracked: Fix Nix build warnings

[Cadigal-displayr]

Unfortunately doesn't make the build pass, as the tests are failing with an error saying that the python tensorflow package isn't installed.
From Jordan:

Unfortunately our Python dependencies are not handled by Nix, because the oldest version of Python Nix supports is 3.9, and we use 3.8 for our R packages, and on the R Server. We tried updating Python to 3.9 so it could be handled via Nix, but that created a dependency hell situation where some Python packages don't support 3.9 (or newer) without a major update, which when we performed that update, resulted in multiple internal R packages having API breakages. Justin W and I are working on that as a low priority task.