Chore: cleanup demos

[chrisdicaprio]

Demos do not work out of the box

example

chrisdc@hutl24256:~/.../COMPONENTS/solvis$ poetry run python scripts/demo.py 
Traceback (most recent call last):
  File "/home/chrisdc/NSHM/DEV/COMPONENTS/solvis/scripts/demo.py", line 71, in <module>
    sol = InversionSolution().from_archive(PurePath(WORK_PATH, name))
  File "/home/chrisdc/NSHM/DEV/COMPONENTS/solvis/solvis/inversion_solution/inversion_solution.py", line 34, in from_archive
    assert Path(instance_or_path).exists()
AssertionError