[stable/2023.1] Add rebuild time for images (#1288)

This is an automated cherry-pick of #1269
/assign mnaser
diff --git a/Dockerfile b/Dockerfile
index 278b418..b623571 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,16 +1,5 @@
-# Copyright (c) 2024 VEXXHOST, Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# 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-License-Identifier: Apache-2.0
+# Atmosphere-Rebuild-Time: 2024-05-30T20:29:01Z
 
 ARG RELEASE