Bump rake from 12.0.0 to 12.3.1

Bumps [rake](https://github.com/ruby/rake) from 12.0.0 to 12.3.1.
- [Release notes](https://github.com/ruby/rake/releases)
- [Changelog](https://github.com/ruby/rake/blob/master/History.rdoc)
- [Commits](ruby/rake@v12.0.0...v12.3.1)

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

Gemfile.lock

@@ -97,7 +97,7 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     rainbow (2.2.1)
-    rake (12.0.0)
+    rake (12.3.1)
     rb-fsevent (0.9.8)
     rb-inotify (0.9.8)
       ffi (>= 0.5.0)