5.0.0: Response streaming

This major release add support for response streaming, currently only implemented by the NodeJS runtimes on AWS. For implementation details, see https://github.com/xp-forge/lambda#response-streaming

• Merged PR #23: Implement streaming lambda responses, as announced by
  AWS in April 2023. Response stream payloads have a soft limit of 20 MB
  as compared to the 6 MB limit for buffered responses. See also #22.
  (@thekid)