Use v4 of dd-trace (supports node v16 and higher)

Author: hansott

sample-apps/express-postgres/package-lock.json

@@ -6,7 +6,7 @@
   "private": true,
   "dependencies": {
     "@aikidosec/firewall": "file:../../build",
-    "dd-trace": "^5.25.0",
+    "dd-trace": "^4.49.0",
     "dotenv": "^16.4.1",
     "express": "^4.19.2",
     "express-async-handler": "^1.2.0",