Build(deps): Bump message_bus from 4.3.7 to 4.3.8 (#23092)

Bumps [message_bus](https://github.com/discourse/message_bus) from 4.3.7 to 4.3.8.
- [Changelog](https://github.com/discourse/message_bus/blob/main/CHANGELOG)
- [Commits](https://github.com/discourse/message_bus/compare/v4.3.7...v4.3.8)

---
updated-dependencies:
- dependency-name: message_bus
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -231,7 +231,7 @@ GEM
     matrix (0.4.2)
     maxminddb (0.1.22)
     memory_profiler (1.0.1)
-    message_bus (4.3.7)
+    message_bus (4.3.8)
       rack (>= 1.1.3)
     method_source (1.0.0)
     mini_mime (1.1.5)