[3.11] gh-99032: datetime docs: Encoding is no longer relevant (GH-93365) (#103788)

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

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(cherry picked from commit 2aa22f7)

Co-authored-by: William Andrea <william.j.andrea@gmail.com>
Co-authored-by: Paul Ganssle <1377457+pganssle@users.noreply.github.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>

Author: 4 people

Doc/library/datetime.rst

@@ -2502,10 +2502,7 @@ 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