Bump logster from 2.4.2 to 2.5.0 (#8538)

Bumps [logster](https://github.com/discourse/logster) from 2.4.2 to 2.5.0.
- [Release notes](https://github.com/discourse/logster/releases)
- [Changelog](https://github.com/discourse/logster/blob/master/CHANGELOG.md)
- [Commits](https://github.com/discourse/logster/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

This new version of Logster has grouping patterns that can be added via the UI to group logs that match into a single row. More details at 24d6cc9742

Gemfile.lock

@@ -171,7 +171,7 @@ GEM
     logstash-event (1.2.02)
     logstash-logger (0.26.1)
       logstash-event (~> 1.2)
-    logster (2.4.2)
+    logster (2.5.0)
     loofah (2.4.0)
       crass (~> 1.0.2)
       nokogiri (>= 1.5.9)