Add TODO for deferred Review comment

Author: Girgias

ext/pdo/pdo_stmt.c

@@ -756,6 +756,7 @@ static bool do_fetch(pdo_stmt_t *stmt, zval *return_value, enum pdo_fetch_type h
 				/* This used to use try_convert_to_string() which would silently support integers, floats, null
 				 * even if any such value could not generate a valid class name, as no class was found it would
 				 * then proceed to use stdClass */
+				// TODO Raise PDO implementation error when the column name is not a string
 				if (Z_TYPE(ce_name_from_column) == IS_STRING) {
 					ce = zend_lookup_class(Z_STR(ce_name_from_column));
 				}