hack: release: re-license under MPLv2

Since this script is not actually used in the final binary deployment
(it's just a useful script), limited file-based copyleft isn't an issue
-- and this license has the benefit that it's compatible with both
Apache 2.0 and GPLv2.

As can be seen in the git history, I am the sole author of this file and
thus there is no issue with relicensing it.

Signed-off-by: Aleksa Sarai <asarai@suse.de>

hack/release.sh

@@ -2,17 +2,9 @@
 # release.sh: configurable signed-artefact release script
 # Copyright (C) 2016-2019 SUSE LLC.
 #
-# 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.
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 set -Eeuo pipefail