Made the dependency on Bundler more specific.

Author: evolve75

Gemfile.lock

@@ -66,7 +66,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  bundler
+  bundler (~> 2.3)
   rake (~> 13.0)
   rdoc (~> 6.0)
   rspec (~> 3.0, > 3.10)

rubytree.gemspec

@@ -74,7 +74,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency 'json', '~> 2.0', '> 2.3.1'
 
   # NOTE: Rake is added as a development and test dependency in the Gemfile.
-  s.add_development_dependency 'bundler', '~> 2.0'
+  s.add_development_dependency 'bundler', '~> 2.3'
   s.add_development_dependency 'rake', '~> 13.0'
   s.add_development_dependency 'rdoc', '~> 6.0'
   s.add_development_dependency 'rspec', '~> 3.0', '> 3.10'