pythongh-108314: PyDict_GetItemString() mentions UTF-8

PyDict_GetItemString(), PyDict_SetItemString() and
PyDict_DelItemString() expects a UTF-8 encoding string for the key.

Doc/c-api/dict.rst

@@ -73,7 +73,7 @@ Dictionary Objects
    .. index:: single: PyUnicode_FromString()
 
    Insert *val* into the dictionary *p* using *key* as a key. *key* should
-   be a :c:expr:`const char*`.  The key object is created using
+   be a :c:expr:`const char*` UTF-8 encoded bytes string.  The key object is created using
    ``PyUnicode_FromString(key)``.  Return ``0`` on success or ``-1`` on
    failure.  This function *does not* steal a reference to *val*.
 
@@ -88,7 +88,8 @@ Dictionary Objects
 
 .. c:function:: int PyDict_DelItemString(PyObject *p, const char *key)
 
-   Remove the entry in dictionary *p* which has a key specified by the string *key*.
+   Remove the entry in dictionary *p* which has a key specified by the UTF-8
+   encoded bytes string *key*.
    If *key* is not in the dictionary, :exc:`KeyError` is raised.
    Return ``0`` on success or ``-1`` on failure.
 
@@ -120,7 +121,8 @@ Dictionary Objects
 .. c:function:: PyObject* PyDict_GetItemString(PyObject *p, const char *key)
 
    This is the same as :c:func:`PyDict_GetItem`, but *key* is specified as a
-   :c:expr:`const char*`, rather than a :c:expr:`PyObject*`.
+   :c:expr:`const char*` UTF-8 encoded bytes string, rather than a
+   :c:expr:`PyObject*`.
 
    .. note::