@slack/bolt@1.4.0

• Adds a much-anticipated enhancement to fire member_joined_channel and member_left_channel events for your own bot (#236) - thanks @TK95 🎉
• Adds the ability to pass in WebClient options into the constructor (#228 and #278) - thanks @koh110 and @aoberoi ⚙️
• Adds Japanese 🇯🇵documentation for Block Kit in modals (#268) - thanks @seratch
• Fixes some typos and mistranslations in the Japanese documentation (#279) - thanks @grgr-dkrk
• Adds view_closed for Block Kit in modals (uses the same view() method) (#276) - thanks @shanedewael
• Removes redundant types for please-upgrade-node (#253) - thanks @43081j
• Adds tests to for the incoming event handler (#269) - thanks @seratch
• Updates logger + documentation to use getLevel() (#270 and #285)- thanks @shanedewael
• Fixes a bug with custom receiver being overwritten when signingSecret was passed into constructor (#271) - thanks @shanedewael
• Adds a maintainer guide (#272) - thanks @shanedewael
• Fixes a JA documentation inconsistency (#273) - thanks @ikenami