chore: release v8.40.0

[github-actions[bot]]

:rocket: v8.40.0

Make sure to use squash & merge when merging! Once this is merged, another job will kick off automatically and publish the package.

:memo: Changelog

8.40.0 (2024-09-02)

Features

• threads 2.0 (#1330) (4b1ffe8)

Bug Fixes

• declare channel.lastMessage return value type as possibly being undefined (#1346) (8e9bc86)