magnum-pi.gemspec in magnum-pi-0.2.0 vs magnum-pi.gemspec in magnum-pi-0.2.1

@@ -23,6 +23,7 @@
   gem.add_development_dependency "rake"
   gem.add_development_dependency "pry"
   gem.add_development_dependency "simplecov"
   gem.add_development_dependency "minitest"
   gem.add_development_dependency "mocha"
+  gem.add_development_dependency "xml-simple"
 end
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