minecraft-servers: fix update.py

Previously, running `nix-shell maintainers/scripts/update.nix --argstr package minecraft-server` caused `versions.json` to be placed in the repository root instead of `pkgs/games/minecraft-servers`.

pkgs/games/minecraft-servers/update.py

@@ -4,6 +4,7 @@
 import json
 from dataclasses import dataclass, field
 from datetime import datetime
+from pathlib import Path
 from typing import Any, Dict, List, Optional
 
 import requests
@@ -150,6 +151,6 @@ def generate() -> Dict[str, Dict[str, str]]:
 
 
 if __name__ == "__main__":
-    with open("versions.json", "w") as file:
+    with open(Path(__file__).parent / "versions.json", "w") as file:
         json.dump(generate(), file, indent=2)
         file.write("\n")