[ruby/ostruct] Bump up ostruct version to 0.5.0

https://github.com/ruby/ostruct/commit/c535a406f8

lib/ostruct.rb

@@ -107,7 +107,7 @@
 # For all these reasons, consider not using OpenStruct at all.
 #
 class OpenStruct
-  VERSION = "0.4.0"
+  VERSION = "0.5.0"
 
   #
   # Creates a new OpenStruct object.  By default, the resulting OpenStruct