Proposal for serializing datetime range for JSON-safe datetime range serialization

[Vishmayraj]

Currently, there is no utility for serializing asyncpg Range datetime objects to JSON-safe strings. Raw datetime objects coming back from the database would crash if returned in a response body, and any future handling would require scattering .isoformat() calls across the codebase.

For the upcoming STAC and DCAT-AP connector that is in the GSOC ideas list, dct:temporal, dct:issued, dct:modified, and STAC item temporal extents all need clean ISO 8601 strings derived from phenomenonTime and resultTime ranges.

def serialize_datetime_range(range_value):
    if range_value is None:
        return None
    start = range_value.lower.isoformat() if range_value.lower else None
    end = range_value.upper.isoformat() if range_value.upper else None
    return {"start": start, "end": end}

I just wanted to ask about the '.isoformat()' everywhere, is that intentional, or is centralizing this the right direction?