Fix license header, add validation

python/scripts/nvbench_json_summary.py

@@ -1,20 +1,6 @@
 #!/usr/bin/env python
-#
-# Copyright 2026 NVIDIA Corporation
-#
-#  Licensed under the Apache License, Version 2.0 with the LLVM exception
-#  (the "License"); you may not use this file except in compliance with
-#  the License.
-#
-#  You may obtain a copy of the License at
-#
-#      http://llvm.org/foundation/relicensing/LICENSE.txt
-#
-#  Unless required by applicable law or agreed to in writing, software
-#  distributed under the License is distributed on an "AS IS" BASIS,
-#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-#  See the License for the specific language governing permissions and
-#  limitations under the License.
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
 from __future__ import annotations