Also test CPython 3.14 (V2) (zauberzeug#5243)

### Motivation

Python 3.14 is released!
https://www.python.org/downloads/release/python-3140/

**Real motivation: zauberzeug#5237 did not work out...**

### Implementation

This pull request adds support for Python 3.14 to the project and
addresses compatibility issues with certain dependencies. The most
important changes are grouped below:

**Python 3.14 support and dependency compatibility:**

* Added Python 3.14 to the test matrix in the GitHub Actions workflow to
ensure CI coverage for the new version.
* Updated the `vbuild` dependency in `pyproject.toml` to use a specific
Git commit for Python 3.14, as the released version is not yet
compatible.
* Added a conditional requirement for `pydantic` in `pyproject.toml` to
exclude versions 2.0–2.11 for Python 3.14 and above, since these
versions are incompatible.

**Test script adjustments:**

* Modified `test_startup.sh` to skip the `examples/ai_interface` test
when running under Python 3.14, due to its reliance on Pydantic V1 which
is not compatible with Python 3.14.

### Progress

- [x] I chose a meaningful title that completes the sentence: "If
applied, this PR will..."
- [x] The implementation is complete (We'll stare at the pipeline to
make that conclusion).
- [x] Pytests have been added (or are not necessary).
- [x] Documentation has been added (or is not necessary).

---------

Co-authored-by: evnchn <>

Author: evnchn

.github/workflows/test.yml

@@ -28,7 +28,7 @@ jobs:
   test:
     strategy:
       matrix:
-        python: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
       fail-fast: false
     runs-on: ubuntu-latest
     timeout-minutes: 40

nicegui/helpers.py

@@ -1,11 +1,11 @@
 from __future__ import annotations
 
-import asyncio
 import functools
 import hashlib
 import os
 import socket
 import struct
+import sys
 import threading
 import time
 import webbrowser
@@ -22,6 +22,11 @@
 
 _shown_warnings: set[str] = set()
 
+if sys.version_info < (3, 13):
+    from asyncio import iscoroutinefunction
+else:
+    from inspect import iscoroutinefunction
+
 
 def warn_once(message: str, *, stack_info: bool = False) -> None:
     """Print a warning message only once."""
@@ -48,7 +53,7 @@ def is_coroutine_function(obj: Any) -> bool:
     """
     while isinstance(obj, functools.partial):
         obj = obj.func
-    return asyncio.iscoroutinefunction(obj)
+    return iscoroutinefunction(obj)
 
 
 def expects_arguments(func: Callable) -> bool: