Fix minor typos in unicode.rst (#149587)

Doc/c-api/unicode.rst

diff --git a/Doc/c-api/unicode.rst b/Doc/c-api/unicode.rst
index 059a7ef..401c99e 100644
--- a/Doc/c-api/unicode.rst
+++ b/Doc/c-api/unicode.rst
@@ -762,7 +762,7 @@
    The string must not have been “used” yet.
    See :c:func:`PyUnicode_New` for details.
 
-   Return the number of written character, or return ``-1`` and raise an
+   Return the number of written characters, or return ``-1`` and raise an
    exception on error.
 
    .. versionadded:: 3.3
@@ -1174,7 +1174,7 @@
    .. versionadded:: 3.3
 
    .. versionchanged:: 3.7
-      The return type is now ``const char *`` rather of ``char *``.
+      The return type is now ``const char *`` rather than ``char *``.
 
    .. versionchanged:: 3.10
       This function is a part of the :ref:`limited API <limited-c-api>`.
@@ -1196,7 +1196,7 @@
    .. versionadded:: 3.3
 
    .. versionchanged:: 3.7
-      The return type is now ``const char *`` rather of ``char *``.
+      The return type is now ``const char *`` rather than ``char *``.
 
 
 UTF-32 Codecs