Fix empty timestamp handling in ISO deserialization

[github-actions]

Summary

• fix SerializationAdapter.load_dict() to treat created_at and expires_at as present when they are empty strings
• parse any present ISO datetime string and raise DeserializationError on invalid values, including ""
• add regression tests that verify empty created_at and expires_at are rejected

Changes

• src/key_value/aio/_utils/serialization.py
  • changed truthiness checks to explicit is not None checks for created_at and expires_at
• tests/utils/test_serialization.py
  • added test_rejects_empty_isoformat_datetime parameterized for both fields

Validation

• python -m uv run pytest tests/utils/test_serialization.py -q

• make test-concise

• Fixes [bug-hunter] Serialization accepts empty created_at/expires_at instead of raising deserialization error #320

AI generated by Issue Assistant

[macroscopeapp]

Raise deserialization errors for empty ISO created_at and expires_at in SerializationAdapter.load_dict in serialization.py

Change truthiness checks to explicit is not None so empty strings reach the datetime parser; add tests that assert DeserializationError for empty ISO timestamps.

📍Where to Start

Start with SerializationAdapter.load_dict in serialization.py.

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Macroscope summarized 009164b.