[ruby/prism] Fix up spacing in generated node.rb

https://github.com/ruby/prism/commit/50d79b734b

prism/templates/lib/prism/node.rb.erb

@@ -331,7 +331,7 @@ module Prism
       end
     end
     <%- else -%>
-    attr_reader :<%= field.name -%>
+    attr_reader :<%= field.name %>
     <%- end -%>
     <%- end -%>
     <%- node.fields.each do |field| -%>