extensions: remove call to gettext.bind_textdomain_codeset().
I added this call originally, mimicking the C plug-ins. Yet in Python, this function is deprecated since Python 3.8 and removed in 3.10. Looking closer in the docs, it looks like Python's gettext module works differently. While all the *gettext() functions return strings in the locale's encoding in C, unless overriden by bind_textdomain_codeset() (therefore we need this call, in order to have locale-independent string encoding), this is not the case in Python, whose gettext() call is already locale-independent. The gettext.bind_textdomain_codeset() function only applies to the specific l*gettext() functions which are deprecated too. Fixes the warning: > goat-exercise-py3.py:37: DeprecationWarning: bind_textdomain_codeset() is deprecated