Build(deps): Bump logster from 2.14.0 to 2.15.0 (#25320)

Bumps [logster](https://github.com/discourse/logster) from 2.14.0 to 2.15.0.
- [Changelog](https://github.com/discourse/logster/blob/main/CHANGELOG.md)
- [Commits](https://github.com/discourse/logster/compare/v2.14.0...v2.15.0)

---
updated-dependencies:
- dependency-name: logster
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Gemfile.lock

@@ -209,7 +209,7 @@ GEM
     logstash-event (1.2.02)
     logstash-logger (0.26.1)
       logstash-event (~> 1.2)
-    logster (2.14.0)
+    logster (2.15.0)
     loofah (2.22.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)