Bump rack from 2.0.1 to 2.0.7 (#1)

Bumps [rack](https://github.com/rack/rack) from 2.0.1 to 2.0.7.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@2.0.1...2.0.7)

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

Author: dependabot[bot]

Gemfile.lock

@@ -104,7 +104,7 @@ GEM
       rack (>= 1.2, < 3)
     psych (2.2.1)
     public_suffix (2.0.4)
-    rack (2.0.1)
+    rack (2.0.7)
     rack-test (0.6.3)
       rack (>= 1.0)
     rails (5.0.0.1)