chore: added licensing to dockerfile

Dockerfile

@@ -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 https://mozilla.org/MPL/2.0/.
+#
 # Multi-stage Dockerfile for Pentest Agent
 # Uses Chainguard Wolfi for minimal attack surface and supply chain security