chore: drop Node.js 18 support for relevant packages

[WilliamBergamin]

Summary

Node.js 18 reached end-of-life on April 30, 2025. This raises the minimum supported Node.js version to 20 for @slack/cli-hooks, @slack/cli-test, @slack/logger, @slack/oauth, @slack/socket-mode, @slack/types,@slack/web-api and @slack/webhook, ahead of the upcoming axios-to-fetch migration.

• Updated engines.node and @types/node from 18 to 20 in both packages
• Split the CI test step so Node 18 runs only the packages that still support it
• All other packages remain unchanged and continue to support Node 18

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[changeset-bot]

🦋 Changeset detected

Latest commit: a4dbb88

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 9 packages

Name	Type
@slack/cli-hooks	Major
@slack/cli-test	Major
@slack/logger	Major
@slack/oauth	Major
@slack/socket-mode	Major
@slack/types	Major
@slack/web-api	Major
@slack/webhook	Major
@slack/rtm-api	Patch

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.38%. Comparing base (4af912d) to head (a4dbb88).
⚠️ Report is 1 commits behind head on v8{webook,web-api}.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           v8{webook,web-api}    #2572   +/-   ##
===================================================
  Coverage               87.38%   87.38%           
===================================================
  Files                      62       62           
  Lines                   10256    10256           
  Branches                  415      415           
===================================================
  Hits                     8962     8962           
  Misses                   1273     1273           
  Partials                   21       21           

Flag	Coverage Δ
cli-hooks	87.38% <ø> (ø)
cli-test	87.38% <ø> (ø)
logger	87.38% <ø> (ø)
oauth	87.38% <ø> (ø)
socket-mode	87.38% <ø> (ø)
web-api	87.38% <ø> (ø)
webhook	87.38% <ø> (ø)

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[zimeg]

@WilliamBergamin Huge thanks for getting this started! Let's note this toward #2359 🐙

I'm approving now but left a few thoughts and comments. Before merging I'm most curious about:

• Freezing the @slack/rtm-api package
• Increasing the minimum npm version

The standard packages of these later versions are so exciting to unlock 🔏 🦕

[zimeg]

🔭 note(non-blocking): We might want to find the LTS version of this minimum? Perhaps not for 20 but in future updates this might guarantee more stable app code:

This release marks the transition of Node.js 24.x into Long Term Support (LTS).

🔗 https://nodejs.org/en/blog/release/v24.11.0

[zimeg]

🧊 suggestion: We might want to keep this package frozen?

Beginning March 31, 2025, we will discontinue support for legacy custom bots.

🔗 https://docs.slack.dev/changelog/2024-09-legacy-custom-bots-classic-apps-deprecation/

[WilliamBergamin]

Good point 💯

[zimeg]

⭐ praise: I understand this is a significant change but should make maintenance much better ongoing!

🪬 thought: We might be confident that developers update to the latest package versions and using the latest Slack features are using more recent versions of node too?

[WilliamBergamin]

I'm not sure of the use case where this package is used standalone, from what I understand it should be used in combination with another one of our packages that now require node 20 🤔