fix: Article slug auto saves (#5524)

- Auto save article slug

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2022_09_26_164441) do
+ActiveRecord::Schema.define(version: 2022_09_30_025317) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_stat_statements"
@@ -134,7 +134,7 @@ ActiveRecord::Schema.define(version: 2022_09_26_164441) do
     t.string "slug", null: false
     t.index ["associated_article_id"], name: "index_articles_on_associated_article_id"
     t.index ["author_id"], name: "index_articles_on_author_id"
-    t.index ["slug"], name: "index_articles_on_slug"
+    t.index ["slug"], name: "index_articles_on_slug", unique: true
   end
 
   create_table "attachments", id: :serial, force: :cascade do |t|