Bump rack from 1.5.2 to 1.6.13

Bumps [rack](https://github.com/rack/rack) from 1.5.2 to 1.6.13.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/main/CHANGELOG.md)
- [Commits](rack/rack@1.5.2...1.6.13)

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

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

Author: dependabot[bot]

Gemfile.lock

@@ -27,7 +27,7 @@ GEM
       mongo_ext (>= 0.18.2)
       rack (>= 1.0.1)
     multi_json (1.7.2)
-    rack (1.5.2)
+    rack (1.6.13)
     rack-protection (1.5.0)
       rack
     rake (10.0.4)