Soft-deprecate `sys.api_version` and the C API's `PYTHON_API_VERSION` about cpython

[hugovk]

There's very little use in the top 8k PyPI projects:

❯ python3 ~/github/misc/cpython/search_pypi_top.py -q . "PYTHON_API_VERSION"
./apsw-3.45.1.0.tar.gz: apsw-3.45.1.0/src/apsw.c: m = apswmodule = PyModule_Create2(&apswmoduledef, PYTHON_API_VERSION);
./Cython-3.0.8.tar.gz: Cython-3.0.8/Cython/Compiler/ModuleNode.py: '%s = Py_InitModule4(%s, %s, %s, 0, PYTHON_API_VERSION); Py_XINCREF(%s);' % (
./gnureadline-8.1.2.tar.gz: gnureadline-8.1.2/Modules/2.x/readline.c: (PyObject *)NULL, PYTHON_API_VERSION);
./gnureadline-8.1.2.tar.gz: gnureadline-8.1.2/Modules/2.x/readline.c: (PyObject *)NULL, PYTHON_API_VERSION);
./MySQL-python-1.2.5.zip: MySQL-python-1.2.5/_mysql.c: (PyObject *)NULL, PYTHON_API_VERSION);
./catboost-1.2.2.tar.gz: catboost-1.2.2/catboost_all_src/contrib/python/numpy/py2/numpy/fft/fftpack_litemodule.c: (PyObject*)NULL,PYTHON_API_VERSION);
./catboost-1.2.2.tar.gz: catboost-1.2.2/catboost_all_src/contrib/python/numpy/py2/numpy/linalg/lapack_litemodule.c: "", (PyObject*)NULL,PYTHON_API_VERSION);
./orjson-3.9.14.tar.gz: orjson-3.9.14/include/cargo/pyo3-ffi-0.20.2/src/modsupport.rs: pub const PYTHON_API_VERSION: i32 = 1013;
./orjson-3.9.14.tar.gz: orjson-3.9.14/include/cargo/pyo3-ffi-0.20.2/src/modsupport.rs: PYTHON_API_VERSION
./orjson-3.9.14.tar.gz: orjson-3.9.14/include/cargo/pyo3-ffi-0.20.2/src/modsupport.rs: PYTHON_API_VERSION
./catboost-1.2.2.tar.gz: catboost-1.2.2/catboost_all_src/contrib/tools/cython/Cython/Compiler/ModuleNode.py: '%s = Py_InitModule4("%s", %s, %s, 0, PYTHON_API_VERSION); Py_XINCREF(%s);' % (
./catboost-1.2.2.tar.gz: catboost-1.2.2/catboost_all_src/contrib/tools/cython/patches/all-changes.patch: '%s = Py_InitModule4("%s", %s, %s, 0, PYTHON_API_VERSION); Py_XINCREF(%s);' % (
./Nuitka-2.0.3.tar.gz: Nuitka-2.0.3/nuitka/code_generation/templates/CodeTemplatesModules.py: PYTHON_API_VERSION
./pyobjc-framework-Metal-10.1.tar.gz: pyobjc-framework-Metal-10.1/Modules/_Metal_inlines.m: m = Py_InitModule4("_inlines", mod_methods, NULL, NULL, PYTHON_API_VERSION);
./pyobjc-framework-SceneKit-10.1.tar.gz: pyobjc-framework-SceneKit-10.1/Modules/_SceneKit_inlines.m: m = Py_InitModule4("_inlines", mod_methods, NULL, NULL, PYTHON_API_VERSION);
./pymqi-1.12.10.tar.gz: pymqi-1.12.10/code/pymqi/pymqe.c: (PyObject*)NULL,PYTHON_API_VERSION);
./ruamel.ordereddict-0.4.15.tar.gz: ruamel.ordereddict-0.4.15/ordereddict.c: // , NULL, PYTHON_API_VERSION
./pyobjc-framework-Cocoa-10.1.tar.gz: pyobjc-framework-Cocoa-10.1/Modules/_Foundation_inlines.m: m = Py_InitModule4("_inlines", mod_methods, NULL, NULL, PYTHON_API_VERSION);
./pyobjc-framework-Cocoa-10.1.tar.gz: pyobjc-framework-Cocoa-10.1/Modules/testhelper.m: m = Py_InitModule4("testhelper", mod_methods, NULL, NULL, PYTHON_API_VERSION);
./pyobjc-framework-CoreAudio-10.1.tar.gz: pyobjc-framework-CoreAudio-10.1/Modules/_CoreAudio_inlines.mm: m = Py_InitModule4("_inlines", mod_methods, NULL, NULL, PYTHON_API_VERSION);
./pycrypto-2.6.1.tar.gz: pycrypto-2.6.1/src/hash_template.c: #if PYTHON_API_VERSION < 1011
./pycrypto-2.6.1.tar.gz: pycrypto-2.6.1/src/block_template.c: #if PYTHON_API_VERSION < 1011
./pycrypto-2.6.1.tar.gz: pycrypto-2.6.1/src/stream_template.c: #if PYTHON_API_VERSION < 1011
./OpenEXR-1.3.9.tar.gz: OpenEXR-1.3.9/OpenEXR.cpp: #if PYTHON_API_VERSION >= 1007

Time: 0:00:27.554846
Found 24 matching lines in 15 projects

❯ python3 ~/github/misc/cpython/search_pypi_top.py -q . "sys\.api_version"
./Kivy-2.3.0.tar.gz: Kivy-2.3.0/kivy/tests/test_benchmark.py: benchmark.extra_info['python_api'] = str(sys.api_version)
./Kivy-2.3.0.tar.gz: Kivy-2.3.0/kivy/tools/benchmark.py: log('Python API      : %s' % sys.api_version)
./Kivy-2.3.0.tar.gz: Kivy-2.3.0/kivy/tools/report.py: report.append('Python API      : %s' % sys.api_version)
./numba-0.59.0.tar.gz: numba-0.59.0/numba/pycc/compiler.py: ir.Constant(lt._int32, sys.api_version)))
./werkzeug-3.0.1.tar.gz: werkzeug-3.0.1/src/werkzeug/testapp.py: "api_version": sys.api_version,

Time: 0:00:27.072367
Found 5 matching lines in 3 projects