python: Remove per-file copyright notices.

These notices are redundant and obscure what are often very short
example scripts.

zulip/integrations/zephyr/zephyr_mirror_backend.py

@@ -1,25 +1,5 @@
 #!/usr/bin/env python
-# Copyright (C) 2012 Zulip, Inc.
-#
-# Permission is hereby granted, free of charge, to any person
-# obtaining a copy of this software and associated documentation files
-# (the "Software"), to deal in the Software without restriction,
-# including without limitation the rights to use, copy, modify, merge,
-# publish, distribute, sublicense, and/or sell copies of the Software,
-# and to permit persons to whom the Software is furnished to do so,
-# subject to the following conditions:
-#
-# The above copyright notice and this permission notice shall be
-# included in all copies or substantial portions of the Software.
-#
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
-# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-# SOFTWARE.
+
 from __future__ import absolute_import
 from typing import IO, Any, Dict, List, Text, Union, Set, Tuple, Optional, cast
 from types import FrameType