gh-99032: datetime docs: Encoding is no longer relevant (#93365)

This removes a section of the `strftime` and `strptime` documentation that refers to a bygone era when `strftime` would return an encoded byte string.

---------

Co-authored-by: Paul Ganssle <1377457+pganssle@users.noreply.github.com>

Doc/library/datetime.rst

@@ -2510,10 +2510,7 @@ Notes:
  Because the format depends on the current locale, care should be taken when
  making assumptions about the output value. Field orderings will vary (for
  example, "month/day/year" versus "day/month/year"), and the output may
- contain Unicode characters encoded using the locale's default encoding (for
- example, if the current locale is ``ja_JP``, the default encoding could be
- any one of ``eucJP``, ``SJIS``, or ``utf-8``; use :meth:`locale.getlocale`
- to determine the current locale's encoding).
+ contain non-ASCII characters.
 
 (2)
  The :meth:`strptime` method can parse years in the full [1, 9999] range, but