RFC 3339 Date/Time Formatting

The `rfc3339` library for Python provides utilities to format `datetime` objects into RFC 3339 compliant strings and to parse such strings back into `datetime` objects. It closely adheres to the RFC 3339 standard, including providing its own UTC `tzinfo` implementation. While the PyPI package `6.2` was last released in 2019, the primary GitHub repository shows recent maintenance activity, indicating it's still actively maintained, albeit with a slow release cadence.