Add Dry Validation (#15)

yookassa.gemspec

@@ -23,5 +23,6 @@ Gem::Specification.new do |spec|
   spec.required_ruby_version = ">= 2.6"
 
   spec.add_runtime_dependency "dry-struct"
+  spec.add_runtime_dependency "dry-validation"
   spec.add_runtime_dependency "http", "~> 5.0.1"
 end