install.rb in cssbundling-rails-0.2.7

- old
+ new

@@ -8,6 +8,7 @@
 
 if (`npx -v`.to_f < 7.1 rescue "Missing")
   say %(Add "scripts": { "build:css": "#{build_script}" } to your package.json), :green
 else
   run %(npm set-script build:css "#{build_script}")
+  run %(yarn build:css)
 end