clarify distinction between datetime module and class in deprecation message

Author: neutrinoceros

Modules/_datetimemodule.c

@@ -5179,9 +5179,9 @@ static PyObject *
 datetime_utcfromtimestamp(PyObject *cls, PyObject *args)
 {
     if (PyErr_WarnEx(PyExc_DeprecationWarning,
-        "datetime.utcfromtimestamp() is deprecated and scheduled for removal "
+        "datetime.datetime.utcfromtimestamp() is deprecated and scheduled for removal "
         "in a future version. Use timezone-aware objects to represent "
-        "datetimes in UTC: datetime.fromtimestamp(timestamp, datetime.UTC).", 1))
+        "datetimes in UTC: datetime.datetime.fromtimestamp(timestamp, datetime.UTC).", 1))
     {
         return NULL;
     }