Add 3.14 to Trove classifiers

[Tinche]

See title.

[webknjaz]

Is there a policy for this in the project? I'm my own, I usually add a new classifier to signal that it's tested against a stable version of that project, not during the alpha phase of CPython..

[hynek]

The policy is that the CI runs against our trove classifiers which implies that it works.

[hynek]

FTR we're waiting for PyO3 adding 3.14 support

[hynek]

Looks like Mypy doesn't like 3.14:

py314-mypy: commands[0]> mypy tests/typing_example.py
Traceback (most recent call last):
  File "/Users/hynek/FOSS/attrs/.tox/py314-mypy/bin/mypy", line 10, in <module>
    sys.exit(console_entry())
             ~~~~~~~~~~~~~^^
  File "/Users/hynek/FOSS/attrs/.tox/py314-mypy/lib/python3.14/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
    ~~~~^^
  File "/Users/hynek/FOSS/attrs/.tox/py314-mypy/lib/python3.14/site-packages/mypy/main.py", line 88, in main
    sources, options = process_options(args, stdout=stdout, stderr=stderr, fscache=fscache)
                       ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/hynek/FOSS/attrs/.tox/py314-mypy/lib/python3.14/site-packages/mypy/main.py", line 1055, in process_options
    parser.add_argument(
    ~~~~~~~~~~~~~~~~~~~^
        "--enable-incomplete-feature",
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<2 lines>...
        help="Enable support of incomplete/experimental features for early preview",
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/argparse.py", line 1562, in add_argument
    formatter = self._get_formatter()
  File "/Library/Frameworks/Python.framework/Versions/3.14/lib/python3.14/argparse.py", line 2729, in _get_formatter
    return self.formatter_class(
           ~~~~~~~~~~~~~~~~~~~~^
        prog=self.prog,
        ^^^^^^^^^^^^^^^
        prefix_chars=self.prefix_chars,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        color=self.color,
        ^^^^^^^^^^^^^^^^^
    )
    ^
TypeError: AugmentedHelpFormatter.__init__() got an unexpected keyword argument 'prefix_chars'
py314-mypy: exit 1 (0.91 seconds) /Users/hynek/FOSS/attrs> mypy tests/typing_example.py pid=68813

[hynek]

So do we want to merge this and tackle these, or are those fixes trivial enough?

XFAIL tests/test_annotations.py::TestAnnotations::test_self_reference[False] - reason: References are changing a lot in 3.14.
[57](https://github.com/python-attrs/attrs/actions/runs/14953583335/job/42006205678?pr=1415#step:8:58)
XFAIL tests/test_annotations.py::TestAnnotations::test_forward_reference[False] - reason: Forward references are changing a lot in 3.14.
[58](https://github.com/python-attrs/attrs/actions/runs/14953583335/job/42006205678?pr=1415#step:8:59)
XFAIL tests/test_setattr.py::TestSetAttr::test_slotted_confused
[59](https://github.com/python-attrs/attrs/actions/runs/14953583335/job/42006205678?pr=1415#step:8:60)
XFAIL tests/test_slots.py::test_slots_cached_property_infers_type - 3.14 returns weird annotation for cached_properies
[60](https://github.com/python-attrs/attrs/actions/runs/14953583335/job/42006205678?pr=1415#step:8:61)
XFAIL tests/test_make.py::TestClassBuilder::test_no_references_to_original_when_using_cached_property - Currently broken on nightly.