python3Packages.litestar: ignore warning in pytest for python>=3.14

Tracking: https://github.com/NixOS/nixpkgs/issues/475732

pkgs/development/python-modules/litestar/default.nix

@@ -2,6 +2,7 @@
   lib,
   buildPythonPackage,
   fetchFromGitHub,
+  pythonAtLeast,
 
   # build-system
   hatchling,
@@ -150,6 +151,11 @@ buildPythonPackage (finalAttrs: {
     "docs/examples/"
   ];
 
+  pytestFlags = lib.optionals (pythonAtLeast "3.14") [
+    # UserWarning: Core Pydantic V1 functionality isn't compatible with Python 3.14 or greater.
+    "-Wignore::UserWarning"
+  ];
+
   disabledTests = [
     # StartupError
     "test_subprocess_async_client"