build(deps): bump rack in /assets/loggregator-load-generator

Bumps [rack](https://github.com/rack/rack) from 3.1.15 to 3.1.16.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v3.1.15...v3.1.16)

---
updated-dependencies:
- dependency-name: rack
  dependency-version: 3.1.16
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

assets/loggregator-load-generator/Gemfile.lock

@@ -5,7 +5,7 @@ GEM
     logger (1.6.1)
     mustermann (3.0.3)
       ruby2_keywords (~> 0.0.1)
-    rack (3.1.15)
+    rack (3.1.16)
     rack-protection (4.1.1)
       base64 (>= 0.1.0)
       logger (>= 1.6.0)