Orjsonl

Changed

- Added tests for `append()` and `extend()` with `newline` set to `False` to achieve 100% coverage.

Added

- Added the `extend()` function, which serializes and appends an iterable of Python objects to a UTF-8-encoded jsonl file.

Changed

- Changed the `append()` function to serialize and append a single Python object to a UTF-8-encoded jsonl file.