Remove unmatched closing parenthesis (GH-139082)

(cherry picked from commit d22b250)

Co-authored-by: Rafael Fontenelle <[email protected]>

Author: rffontenelle

Doc/c-api/unicode.rst

@@ -731,7 +731,7 @@ APIs:
    Return ``0`` on success, ``-1`` on error with an exception set.
 
    This function checks that *unicode* is a Unicode object, that the index is
-   not out of bounds, and that the object's reference count is one).
+   not out of bounds, and that the object's reference count is one.
    See :c:func:`PyUnicode_WRITE` for a version that skips these checks,
    making them your responsibility.