[3.14] gh-139988: fix a leak when failing to create a Union type (GH-139990) (#139993)

gh-139988: fix a leak when failing to create a Union type (GH-139990)
(cherry picked from commit 6710156bd2)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Objects/unionobject.c

@@ -474,11 +474,13 @@ _Py_union_from_tuple(PyObject *args)
     }
     if (PyTuple_CheckExact(args)) {
         if (!unionbuilder_add_tuple(&ub, args)) {
+            unionbuilder_finalize(&ub);
             return NULL;
         }
     }
     else {
         if (!unionbuilder_add_single(&ub, args)) {
+            unionbuilder_finalize(&ub);
             return NULL;
         }
     }