Allow to install 2.4.0dev(trunk)

Author: hsbt

xmlrpc.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |spec|
   spec.bindir        = "exe"
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
-  spec.required_ruby_version = ">= 2.4.0"
+  spec.required_ruby_version = ">= 2.4.0dev"
 
   spec.add_development_dependency "bundler"
   spec.add_development_dependency "rake"