Keep tuple API for os.get_terminal_size()

pip is not ready for this change:

$ PYTHONWARNINGS=error env/bin/python -Werror -m pip install setuptools -v
Traceback (most recent call last):
  File "/home/vstinner/python/main/Lib/runpy.py", line 201, in _run_module_as_main
    return _run_code(code, main_globals, None,
                     "__main__", mod_spec)
  File "/home/vstinner/python/main/Lib/runpy.py", line 87, in _run_code
    exec(code, run_globals)
    ~~~~^^^^^^^^^^^^^^^^^^^
  File "/home/vstinner/python/main/env/lib/python3.16t/site-packages/pip/__main__.py", line 24, in <module>
    sys.exit(_main())
             ~~~~~^^
  File "/home/vstinner/python/main/env/lib/python3.16t/site-packages/pip/_internal/cli/main.py", line 70, in main
    cmd_name, cmd_args = parse_command(args)
                         ~~~~~~~~~~~~~^^^^^^
  File "/home/vstinner/python/main/env/lib/python3.16t/site-packages/pip/_internal/cli/main_parser.py", line 71, in parse_command
    parser = create_main_parser()
  File "/home/vstinner/python/main/env/lib/python3.16t/site-packages/pip/_internal/cli/main_parser.py", line 26, in create_main_parser
    formatter=UpdatingDefaultsHelpFormatter(),
              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/vstinner/python/main/env/lib/python3.16t/site-packages/pip/_internal/cli/parser.py", line 45, in __init__
    kwargs["width"] = shutil.get_terminal_size()[0] - 2
                      ~~~~~~~~~~~~~~~~~~~~~~~~~~^^^
DeprecationWarning: tuple API is deprecated, use named attributes

Author: vstinner

Modules/posixmodule.c

@@ -18973,7 +18973,7 @@ posixmodule_exec(PyObject *m)
 #endif
 
     /* initialize TerminalSize_info */
-    state->TerminalSizeType = (PyObject *)_PyStructSequence_NewType(&TerminalSize_desc, 0, 1);
+    state->TerminalSizeType = (PyObject *)PyStructSequence_NewType(&TerminalSize_desc);
     if (PyModule_AddObjectRef(m, "terminal_size", state->TerminalSizeType) < 0) {
         return -1;
     }