Support for Python 3.14

Thank you very much for your package which works great on my Python 3.13.5:

(base) C:\Users\Akira>python -V
Python 3.13.5

(base) C:\Users\Akira>pip show zstandard
Name: zstandard
Version: 0.25.0
Summary: Zstandard bindings for Python
Home-page: https://github.com/indygreg/python-zstandard
Author:
Author-email: Gregory Szorc <gregory.szorc@gmail.com>
License-Expression: BSD-3-Clause
Location: C:\Users\Akira\anaconda3\Lib\site-packages
Requires:
Required-by: conda, conda_index, conda_package_streaming

On the other hand, I could not install pgzip on Python 3.14.2:

(base) C:\Users\Akira>conda activate myenv

(myenv) C:\Users\Akira>python -V
Python 3.14.2

(myenv) C:\Users\Akira>pip install zstandard
Traceback (most recent call last):
  File "C:\Users\Akira\anaconda3\envs\myenv\Scripts\pip-script.py", line 9, in <module>
    sys.exit(main())
             ~~~~^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\cli\main.py", line 65, in main
    cmd_name, cmd_args = parse_command(args)
                         ~~~~~~~~~~~~~^^^^^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\cli\main_parser.py", line 79, in parse_command
    general_options, args_else = parser.parse_args(args)
                                 ~~~~~~~~~~~~~~~~~^^^^^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\optparse.py", line 1361, in parse_args
    values = self.get_default_values()
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\cli\parser.py", line 283, in get_default_values
    self.config.load()
    ~~~~~~~~~~~~~~~~^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\configuration.py", line 126, in load
    self._load_config_files()
    ~~~~~~~~~~~~~~~~~~~~~~~^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\configuration.py", line 257, in _load_config_files
    config_files = dict(self.iter_config_files())
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\configuration.py", line 352, in iter_config_files
    config_files = get_configuration_files()
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\configuration.py", line 72, in get_configuration_files
    os.path.join(path, CONFIG_BASENAME) for path in appdirs.site_config_dirs("pip")
                                                    ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_internal\utils\appdirs.py", line 47, in site_config_dirs
    dirval = _appdirs.site_config_dir(appname, appauthor=False, multipath=True)
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_vendor\platformdirs\__init__.py", line 146, in site_config_dir
    ).site_config_dir
      ^^^^^^^^^^^^^^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_vendor\platformdirs\windows.py", line 67, in site_config_dir
    return self.site_data_dir
           ^^^^^^^^^^^^^^^^^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_vendor\platformdirs\windows.py", line 56, in site_data_dir
    path = os.path.normpath(get_win_folder("CSIDL_COMMON_APPDATA"))
                            ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Akira\anaconda3\envs\myenv\Lib\site-packages\pip\_vendor\platformdirs\windows.py", line 209, in get_win_folder_from_registry
    directory, _ = winreg.QueryValueEx(key, shell_folder_name)
                   ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [WinError 2] The system cannot find the file specified

Could you please have a check on this issue?

Inizia riproducendo il malfunzionamento segnalato di pip install zstandard su Windows con Python 3.14.2 e confrontalo con la configurazione funzionante di Python 3.13.5. Determina se il malfunzionamento riguarda l’installazione del pacchetto o il traceback mostrato di pip/platformdirs; il lavoro è completato quando il pacchetto può essere installato correttamente su Python 3.14.