run_release.py broken for 3.12 and earlier because of bytecode magic number check

[Yhg1s]

During the release of 3.12.5:

💥 Checking the magic number is up-to-date
Traceback (most recent call last):
 File "./run_release.py", line 1283, in <module>
 main()
 File "./run_release.py", line 1279, in main
 automata.run()
 File "./run_release.py", line 244, in run
 raise e from None
 File "./run_release.py", line 241, in run
 self.current_task(self.db)
 File "release.py", line 126, in __call__
 return getattr(self, "function")(db)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "./run_release.py", line 402, in check_magic_number
 magic_actual = get_magic(magic_actual_file, magic_actual_re)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "./run_release.py", line 391, in get_magic
 if m := regex.search(source.read_text()):
 ^^^^^^^^^^^^^^^^^^
 File "/usr/lib/python3.11/pathlib.py", line 1059, in read_text
 with self.open(mode='r', encoding=encoding, errors=errors) as f:
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "/usr/lib/python3.11/pathlib.py", line 1045, in open
 return io.open(self, mode, buffering, encoding, errors, newline)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: 'cpython/Include/internal/pycore_magic_number.h'

[Yhg1s]

Actually, it's also broken for 3.13 because pycore_magic_number.h doesn't exist there, either.

[Yhg1s]

FYI: PR that added this feature: #153