Bump rack from 2.0.7 to 2.0.8 (#2)

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](https://github.com/rack/rack/compare/2.0.7...2.0.8)

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

Gemfile.lock

@@ -53,7 +53,7 @@ GEM
       oauth2 (~> 1.1)
       omniauth (~> 1.9)
     public_suffix (3.0.3)
-    rack (2.0.7)
+    rack (2.0.8)
     rake (10.5.0)
     rspec (3.8.0)
       rspec-core (~> 3.8.0)