Chore: Update playground package.json to private (#20)

Author: Adammatthiesen

packages/playground/package.json

@@ -2,6 +2,7 @@
   "name": "playground",
   "type": "module",
   "version": "0.0.1",
+  "private": "true",
   "scripts": {
     "dev": "astro dev",
     "start": "astro dev",
@@ -21,4 +22,4 @@
     "marked-alert": "2.0.1",
     "typescript": "^5.3.3"
   }
-}
+}