Kino 0.1.3

• Non-String response header names and values (booleans, numbers, symbols)
  are now serialized with to_s, matching Puma, instead of failing the
  request with a TypeError. (Fixes [#3], reported by Max Erkin @rus-max)
• New on_error directive: a callable invoked with (exception, env) when
  a worker catches an app or delivery error, after the client got its 500.
  Delivery errors (unserializable header, a body that raised mid-stream)
  happen after the middleware stack returned, so this hook is the only
  place an error tracker can see them. Handler failures are logged and
  swallowed; in :ractor mode the handler must be Ractor-shareable. (Fixes [#3], reported by Max Erkin @rus-max)
• Worker error log lines now include the exception backtrace (first 12
  frames), not just the exception class and message.
• A streaming body that raises mid-stream now aborts the connection
  instead of finishing the chunked response cleanly, so a client can no
  longer mistake a truncated response for a complete one.