Bump rack from 2.0.7 to 2.0.8

Bumps [rack](https://github.com/rack/rack) from 2.0.7 to 2.0.8.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@2.0.7...2.0.8)

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

Gemfile.lock

@@ -70,7 +70,7 @@ GEM
     multipart-post (2.1.1)
     mustermann (1.0.3)
     public_suffix (3.1.0)
-    rack (2.0.7)
+    rack (2.0.8)
     rack-protection (2.0.5)
       rack
     sinatra (2.0.5)