[ruby/erb] Use a ruby-lang alias on spec.email

https://github.com/ruby/erb/commit/39414f32a5

lib/erb.gemspec

@@ -9,7 +9,7 @@ Gem::Specification.new do |spec|
   spec.name          = 'erb'
   spec.version       = ERB.const_get(:VERSION, false)
   spec.authors       = ['Masatoshi SEKI', 'Takashi Kokubun']
-  spec.email         = ['seki@ruby-lang.org', 'takashikkbn@gmail.com']
+  spec.email         = ['seki@ruby-lang.org', 'k0kubun@ruby-lang.org']
 
   spec.summary       = %q{An easy to use but powerful templating system for Ruby.}
   spec.description   = %q{An easy to use but powerful templating system for Ruby.}