Fix indentation of postcss-import require

Fixes the indentation of `require('postcss-import')` to match the rest of the required plugins.

Author: danielwestendorf

lib/install/tailwindcss_with_webpacker.rb

@@ -13,7 +13,7 @@
 say "Adding minimal configuration for Tailwind CSS to work properly"
 directory Pathname.new(__dir__).join("stylesheets"), Webpacker.config.source_path.join("stylesheets")
 
-insert_into_file "postcss.config.js", "require('tailwindcss'),\n\t", before: "require('postcss-import')"
+insert_into_file "postcss.config.js", "require('tailwindcss'),\n\t", before: "  require('postcss-import')"
 
 if APPLICATION_LAYOUT_PATH.exist?
   say "Add Tailwindcss include tags in application layout"