Merge pull request #150 from cognitedata/release/0.2.4

## Bump
- [ ] Major
- [ ] Minor
- [x] Patch

## Changelog

### Fixed
- `producedAt` was written as a Unix millisecond integer (`1778152091557`); the Records API requires an ISO 8601 datetime string — converted using `datetime.now(tz=timezone.utc)`
