Bug 1622328 - artifact_commands.py: Add the license r=rstewart

Depends on D66805

Differential Revision: https://phabricator.services.mozilla.com/D66806

--HG--
extra : moz-landing-system : lando

python/mozbuild/mozbuild/artifact_commands.py

@@ -1,3 +1,7 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 from __future__ import absolute_import
 import argparse
 import hashlib