event_time_microseconds field changes to Decimal64 from UInt64

Why it matters

Changing the event_time_microseconds field to Decimal64 improves precision and reliability when storing microsecond-accurate event timestamps, solving potential precision or overflow issues with UInt64.

How to use it

Users automatically benefit from this change when working with the event_time_microseconds field, as it now stores values using the Decimal64 type internally. No manual action is required to enable this update.