Fix rails engine gemspac format

`spec.license` indendation is messed up. This PF fixes indentation.

Author: dixpac

railties/lib/rails/generators/rails/plugin/templates/%name%.gemspec.tt

@@ -8,9 +8,9 @@ Gem::Specification.new do |spec|
   spec.homepage    = "TODO"
   spec.summary     = "TODO: Summary of <%= camelized_modules %>."
   spec.description = "TODO: Description of <%= camelized_modules %>."
-  <% unless inside_application? -%>
+  <%- unless inside_application? -%>
   spec.license     = "MIT"
-  <% end -%>
+  <%- end -%>
 
   # Prevent pushing this gem to RubyGems.org. To allow pushes either set the "allowed_push_host"
   # to allow pushing to a single host or delete this section to allow pushing to any host.