doc: Update open() default encoding docs for Python 3.15

Fixes #148603

Author: dagangtj

Doc/library/functions.rst

@@ -644,7 +644,7 @@ are always available.  They are listed here in alphabetical order.
    If the given source is a string, then leading and trailing spaces and tabs
    are stripped.
 
-   See :func:`ast.literal_eval` for a function that can safely evaluate strings
+   See :func:`ast.literal_eval` for a function to evaluate strings
    with expressions containing only literals.
 
    .. audit-event:: exec code_object eval
@@ -1373,8 +1373,7 @@ are always available.  They are listed here in alphabetical order.
    already exists), ``'x'`` for exclusive creation, and ``'a'`` for appending
    (which on *some* Unix systems, means that *all* writes append to the end of
    the file regardless of the current seek position).  In text mode, if
-   *encoding* is not specified the encoding used is platform-dependent:
-   :func:`locale.getencoding` is called to get the current locale encoding.
+   *encoding* is not specified, UTF-8 is used.
    (For reading and writing raw bytes use binary mode and leave
    *encoding* unspecified.)  The available modes are:
 
@@ -1404,7 +1403,7 @@ are always available.  They are listed here in alphabetical order.
    argument) return contents as :class:`bytes` objects without any decoding.  In
    text mode (the default, or when ``'t'`` is included in the *mode* argument),
    the contents of the file are returned as :class:`str`, the bytes having been
-   first decoded using a platform-dependent encoding or using the specified
+   first decoded using UTF-8 or using the specified
    *encoding* if given.
 
    .. note::
@@ -1433,9 +1432,8 @@ are always available.  They are listed here in alphabetical order.
      described above for binary files.
 
    *encoding* is the name of the encoding used to decode or encode the file.
-   This should only be used in text mode.  The default encoding is platform
-   dependent (whatever :func:`locale.getencoding` returns), but any
-   :term:`text encoding` supported by Python can be used.
+   This should only be used in text mode.  The default encoding is UTF-8,
+   but any :term:`text encoding` supported by Python can be used.
    See the :mod:`codecs` module for the list of supported encodings.
 
    *errors* is an optional string that specifies how encoding and decoding
@@ -1549,6 +1547,9 @@ are always available.  They are listed here in alphabetical order.
       * On Windows, opening a console buffer may return a subclass of
         :class:`io.RawIOBase` other than :class:`io.FileIO`.
 
+   .. versionchanged:: 3.15
+      The default encoding is now UTF-8, rather than locale-dependent.
+
    .. versionchanged:: 3.11
       The ``'U'`` mode has been removed.
 
@@ -1754,7 +1755,7 @@ are always available.  They are listed here in alphabetical order.
             self.age = age
 
          def __repr__(self):
-            return f"Person('{self.name}', {self.age})"
+            return f"Person({self.name!r}, {self.age!r})"
 
 
 .. function:: reversed(object, /)