validate_metadata: reject future lastVerified timestamps

[hbelmiro]

check_date_time() in scripts/validate_metadata/validate_metadata.py currently allows lastVerified values in the future because (now - dt).days becomes negative and will never be >= 365. This lets assets bypass the "fresh within 12 months" policy and can also cause check_component_freshness.py to treat future-dated assets as extra-fresh (negative age).

Future timestamps should be explicitly rejected.

Reference: #180 (comment)

[hbelmiro]

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[filip-komarzyniec]

I can take this on 🙋🏼‍♂️However I'd recommend finishing up merge of #180 first, as these changes will be conflicting.

[filip-komarzyniec]

/assign

[alyssacgoins]

@filip-komarzyniec hey thanks for your interest on this issue! Are you still planning to raise a PR here?

cc @hbelmiro