version 1.4.0

This release upgrades the underlying slack-sdk package from 3.3 to 3.4 (or higher). Refer to the package's release note for more details: https://github.com/slackapi/python-slack-sdk/releases/tag/v3.4.0

Changes

• #243 Upgrade slack-sdk to 3.4 - Thanks @seratch

References

• milestone: https://github.com/slackapi/bolt-python/milestone/21?closed=1
• diff: v1.3.2...v1.4.0