Bump rack from 2.2.19 to 2.2.20

Bumps [rack](https://github.com/rack/rack) from 2.2.19 to 2.2.20.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](https://github.com/rack/rack/compare/v2.2.19...v2.2.20)

---
updated-dependencies:
- dependency-name: rack
  dependency-version: 2.2.20
  dependency-type: indirect
...

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

Gemfile.lock

@@ -583,7 +583,7 @@ GEM
       railties (>= 4.2)
     raabro (1.4.0)
     racc (1.8.1)
-    rack (2.2.19)
+    rack (2.2.20)
     rack-mini-profiler (2.3.4)
       rack (>= 1.2.0)
     rack-oauth2 (2.2.1)