Potential problems in ``validate_data.py`` derived from unused items

[oesteban]

First,

diagnostics-NME/scripts/validate_data.py

Line 9 in 6653c80

import sys

where sys is imported but never used.

Later,

diagnostics-NME/scripts/validate_data.py

Line 83 in 6653c80

d_pth = list(data_pth.glob("**/*"))

assigns d_pth and it's never used.