feat: include base64 gem

Author: rubysamurai

cryptology.gemspec

@@ -24,6 +24,8 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = Gem::Requirement.new('>= 2.4.0')
 
+  spec.add_runtime_dependency 'base64', '>= 0.2.0'
+
   spec.add_development_dependency 'rake',  '>= 12.0'
   spec.add_development_dependency 'rspec', '>= 3.6'
 end