[doc] Fix typo c-api/exceptions.rst (GH-27847) (GH-27919)

Co-authored-by: Tianqing Peng <pengtianqing@yimian.com.cn>
(cherry picked from commit dcbf7ff)

Co-authored-by: Sunny Bean <ptq008@gmail.com>

Doc/c-api/exceptions.rst

@@ -100,7 +100,7 @@ For convenience, some of these functions will always return a
    This is the most common way to set the error indicator.  The first argument
    specifies the exception type; it is normally one of the standard exceptions,
    e.g. :c:data:`PyExc_RuntimeError`.  You need not increment its reference count.
-   The second argument is an error message; it is decoded from ``'utf-8``'.
+   The second argument is an error message; it is decoded from ``'utf-8'``.
 
 
 .. c:function:: void PyErr_SetObject(PyObject *type, PyObject *value)