[3.13] marshal docs: Remove reference to "Sun" (GH-119161) (#119167)

 Nobody has been using a Sun machine for a long time. When I saw this sentence in a lightning talk just now, I thought it was talking about sending Python code on a spacecraft. (cherry picked from commit 697465f) Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Author: miss-islington

Doc/library/marshal.rst

@@ -10,7 +10,7 @@
 This module contains functions that can read and write Python values in a binary
 format. The format is specific to Python, but independent of machine
 architecture issues (e.g., you can write a Python value to a file on a PC,
-transport the file to a Sun, and read it back there). Details of the format are
+transport the file to a Mac, and read it back there). Details of the format are
 undocumented on purpose; it may change between Python versions (although it
 rarely does). [#]_