chore(deps): update node.js to v20.13.1

Author: renovate[bot]

package.json

@@ -2,7 +2,7 @@
   "name": "@systemd/root",
   "version": "1.0.0",
   "engines": {
-    "node": "20.x",
+    "node": "20.13.1",
     "yarn": "4.x"
   },
   "type": "module",

packages/conf/package.json

@@ -2,7 +2,7 @@
   "name": "@systemd-js/conf",
   "version": "0.1.2",
   "engines": {
-    "node": "20.x",
+    "node": "20.13.1",
     "yarn": "4.x"
   },
   "repository": {