`locale.getdefaultlocale()` is deprecated

[jwodder]

nipype uses the locale.getdefaultlocale() function here and here. However, this function was deprecated in Python 3.11 and will be removed in Python 3.13. It should be replaced with either locale.getpreferredencoding() or locale.getencoding().

[effigies]

I guesss getpreferredencoding is the better option for now, as we getencoding() is 3.11+. Unless there's an argument for using getencoding and having a fallback?