Fix rat-exclides and issue template licence (#22550)

.rat-excludes

@@ -113,3 +113,8 @@ chart/values_schema.schema.json
 
 # autogenerated docker-compose.env
 scripts/ci/docker-compose/_docker_compose.env
+
+# Exclude robots from rat check
+airflow/www/static/robots.txt
+# Auto-generated files
+scripts/ci/installed_providers.txt

dev/ISSUE_TEMPLATE.md.jinja2

@@ -1,4 +1,21 @@
+<!--
+ Licensed to the Apache Software Foundation (ASF) under one
+ or more contributor license agreements.  See the NOTICE file
+ distributed with this work for additional information
+ regarding copyright ownership.  The ASF licenses this file
+ to you 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.
+-->
 
 We have a kind request for all the contributors to the latest [Apache Airflow RC {{version}}](https://pypi.org/project/apache-airflow/{{version}}/).