user_id file changed to unsigned bigInteger.

src/migrations/create_ratings_table.php

@@ -15,7 +15,7 @@ public function up()
  $table->timestamps();
  $table->integer('rating');
  $table->morphs('rateable');
- $table->unsignedInteger('user_id')->index();
+ $table->bigInteger('user_id')->unsigned();
  $table->index('rateable_id');
  $table->index('rateable_type');
  $table->foreign('user_id')->references('id')->on('users');