[3.13] Fix grammatical typos in documentation (GH-154181) (#154193)

(cherry picked from commit 40f7fbf)

Author: bontail

Doc/library/ast.rst

@@ -1301,7 +1301,7 @@ Control flow
 
    ``try`` blocks which are followed by ``except*`` clauses. The attributes are the
    same as for :class:`Try` but the :class:`ExceptHandler` nodes in ``handlers``
-   are interpreted as ``except*`` blocks rather then ``except``.
+   are interpreted as ``except*`` blocks rather than ``except``.
 
    .. doctest::
 

Doc/library/sys.rst

@@ -1835,7 +1835,7 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    returned by the :func:`open` function.  Their parameters are chosen as
    follows:
 
-   * The encoding and error handling are is initialized from
+   * The encoding and error handling are initialized from
      :c:member:`PyConfig.stdio_encoding` and :c:member:`PyConfig.stdio_errors`.
 
      On Windows, UTF-8 is used for the console device.  Non-character