Fix deprecated loader call

package.json

@@ -5,7 +5,7 @@
   "type": "module",
   "scripts": {
     "lint": "eslint ./backend",
-    "test:backend": "node --loader tsx --test backend/tests/*.test.ts",
+    "test:backend": "node --import tsx --test backend/tests/*.test.ts",
     "test": "npm run test:backend",
     "dev:backend": "rbt dev run"
   },