update copyright

Signed-off-by: Fullstop000 <[email protected]>

src/group/mod.rs

@@ -1,4 +1,4 @@
-// Copyright 2019 PingCAP, Inc.
+// Copyright 2019 TiKV Project Authors. Licensed under Apache-2.0.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -8,6 +8,7 @@
 //
 // 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.