Relax the versions of dependencies

Author: mrkn

matplotlib.gemspec

@@ -23,8 +23,8 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "pycall", ">= 1.0.0"
 
-  spec.add_development_dependency "bundler", "~> 1.13"
-  spec.add_development_dependency "rake", "~> 10.0"
-  spec.add_development_dependency "rspec", "~> 3.0"
+  spec.add_development_dependency "bundler", ">= 1.17.2"
+  spec.add_development_dependency "rake"
+  spec.add_development_dependency "rspec"
   spec.add_development_dependency "pry"
 end