Use an anonymous block parameter in Module#delegate

`...` generates an anonymous block, it's basically a shortcut
for `*, **, &`. So to look more similar to tools that introspect
method signatures, it's best to continue to use an anonymous block.

Author: byroot

activesupport/lib/active_support/core_ext/module/delegation.rb

@@ -237,7 +237,7 @@ def delegate(*methods, to: nil, prefix: nil, allow_nil: nil, private: nil, as: n
               "..."
             else
               defn = parameters.filter_map { |type, arg| arg if type == :req }
-              defn << "&block"
+              defn << "&"
               defn.join(", ")
             end
           else