chore: Add missing license header.

Author: tjholm

nitric/resources/base.py

@@ -1,3 +1,21 @@
+#
+# Copyright (c) 2021 Nitric Technologies Pty Ltd.
+#
+# This file is part of Nitric Python 3 SDK.
+# See https://github.com/nitrictech/python-sdk for further info.
+#
+# 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.
+#
 from __future__ import annotations
 
 import asyncio