Bump rubytree from 2.0.2 to 2.0.3

Bumps [rubytree](https://github.com/evolve75/RubyTree) from 2.0.2 to 2.0.3.
- [Release notes](https://github.com/evolve75/RubyTree/releases)
- [Changelog](https://github.com/evolve75/RubyTree/blob/master/API-CHANGES.md)
- [Commits](https://github.com/evolve75/RubyTree/compare/R2.0.2...R2.0.3)

---
updated-dependencies:
- dependency-name: rubytree
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Gemfile.lock

@@ -444,7 +444,7 @@ GEM
     ruby-vips (2.2.0)
       ffi (~> 1.12)
     ruby2_keywords (0.0.5)
-    rubytree (2.0.2)
+    rubytree (2.0.3)
       json (~> 2.0, > 2.3.1)
     rubyzip (2.3.2)
     sassc (2.4.0)