chore: set license headers

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

hack/dockerfiles/license.Dockerfile

@@ -1,5 +1,19 @@
 # syntax=docker/dockerfile:1
 
+# Copyright 2023 actions-toolkit authors
+#
+# 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.
+
 ARG LICENSE_HOLDER="actions-toolkit authors"
 ARG LICENSE_TYPE="apache"
 ARG LICENSE_FILES=".*\(Dockerfile\|Makefile\|\.js\|\.ts\|\.hcl\|\.sh\)"