Babel fails to handle C locale properly

The "C" locale is the only one that is guaranteed to be available on all systems, however Babel does not handle it correctly: ``` 13:12:25: File "/home/xxxx/venv/lib/python3.12/site-packages/babel/core.py", line 427, in parse 13:12:25: raise UnknownLocaleError(input_id) 13:12:25: babel.core.UnknownLocaleError: unknown locale 'c' ``` This is problematic if a python program that uses Babel is running with the C locale set.