Release 3.1.0

Release 2.27.1

- [API] New knob to set outgoing packet batch size.
- Aborted connection now become tickable immediately.
- Abort connection when HTTP/3 frame cannot be opened (can only happen
when malloc fails).

Release 2.23.2

- Add QPACK stats collection and experimentation mode, see the new
es_qpack_experiment setting.
- Log busy connection stats every second using the new "conn-stats"
log module.
- Log about skipping only once.
- Update HTTP/3 greased frame type formula.
- Use ls-qpack v2.2.1.