Bump rack from 1.6.5 to 1.6.13 in /hooks/ruby/delete-repository-event (github#317)

Bumps [rack](https://github.com/rack/rack) from 1.6.5 to 1.6.13.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@1.6.5...1.6.13)

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

hooks/ruby/delete-repository-event/Gemfile.lock

@@ -9,9 +9,9 @@ GEM
     octokit (4.6.2)
       sawyer (~> 0.8.0, >= 0.5.3)
     public_suffix (2.0.5)
-    rack (1.6.5)
+    rack (1.6.13)
     rack-protection (1.5.5)
-      rack (1.6.11)
+      rack
     sawyer (0.8.1)
       addressable (>= 2.3.5, < 2.6)
       faraday (~> 0.8, < 1.0)