Bump rack from 2.2.18 to 2.2.19 in /benchmarks/lobsters (#415)

Bumps [rack](https://github.com/rack/rack) from 2.2.18 to 2.2.19.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v2.2.18...v2.2.19)

---
updated-dependencies:
- dependency-name: rack
  dependency-version: 2.2.19
  dependency-type: indirect
...

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

Author: dependabot[bot]

benchmarks/lobsters/Gemfile.lock

@@ -190,7 +190,7 @@ GEM
       stringio
     public_suffix (6.0.2)
     racc (1.8.1)
-    rack (2.2.18)
+    rack (2.2.19)
     rack-attack (6.7.0)
       rack (>= 1.0, < 4)
     rack-mini-profiler (4.0.1)