Only include ERB templates by default

Using `./app/views/**/*` includes transient files like vim backup files and generates errors like that seen in rails/rails#44646.

Author: pixeltrix

lib/install/tailwind.config.js

@@ -4,7 +4,7 @@ module.exports = {
   content: [
     './app/helpers/**/*.rb',
     './app/javascript/**/*.js',
-    './app/views/**/*'
+    './app/views/**/*.erb'
   ],
   theme: {
     extend: {