Raise yard minimum version to 0.9.42

Tighten the gemspec and lockfile dependency floor so the manifest no longer permits vulnerable YARD releases while keeping master on the already-locked 0.9.42 version.

Author: evolve75

Gemfile.lock

@@ -91,7 +91,7 @@ DEPENDENCIES
   simplecov (~> 0.22)
   simplecov-lcov (~> 0.8)
   test-unit (~> 3.6)
-  yard (~> 0.0, >= 0.9.37)
+  yard (~> 0.0, >= 0.9.42)
 
 BUNDLED WITH
    2.3.4

rubytree.gemspec

@@ -78,7 +78,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'simplecov', '~> 0.22'
   s.add_development_dependency 'simplecov-lcov', '~> 0.8'
   s.add_development_dependency 'test-unit', '~> 3.6'
-  s.add_development_dependency 'yard', '~> 0.0', '>= 0.9.37'
+  s.add_development_dependency 'yard', '~> 0.0', '>= 0.9.42'
 
   s.post_install_message = <<-END_MESSAGE
     ========================================================================