chore: auto-install npm deps

Author: joscha

deno.jsonc

@@ -13,6 +13,7 @@
         "fetch-mock": "npm:fetch-mock@^11.1.3",
         "typescript": "npm:typescript@^5.4.5"
     },
+    "nodeModulesDir": "auto",
     "tasks": {
         "build": "deno run -A scripts/build_npm.ts",
         "check": "deno check src/**/*.ts",