Bump rack from 2.2.8 to 2.2.9 in /resque-web

Bumps [rack](https://github.com/rack/rack) from 2.2.8 to 2.2.9.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@v2.2.8...v2.2.9)

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

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

resque-web/Gemfile.lock

@@ -13,7 +13,7 @@ GEM
     mustermann (2.0.2)
       ruby2_keywords (~> 0.0.1)
     raabro (1.4.0)
-    rack (2.2.8)
+    rack (2.2.9)
     rack-protection (2.2.3)
       rack
     rake (12.3.3)