Bump rake from 12.3.2 to 13.0.6 in /examples/rails_app

Bumps [rake](https://github.com/ruby/rake) from 12.3.2 to 13.0.6.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](ruby/rake@v12.3.2...v13.0.6)

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

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

Author: dependabot[bot]

examples/rails_app/Gemfile.lock

@@ -136,7 +136,7 @@ GEM
       method_source
       rake (>= 0.8.7)
       thor (>= 0.19.0, < 2.0)
-    rake (12.3.2)
+    rake (13.0.6)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.0)
       ffi (~> 1.0)