Add mergify rules.

.mergify.yml

@@ -0,0 +1,30 @@
+#
+# 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.
+pull_request_rules:
+  - name: Require approval from UHS maintainers
+    conditions:
+      - "#approved-reviews-by>=1"
+    actions:
+      post_check:
+        success_conditions:
+          - or:
+              - "#approved-reviews-by>=2"
+              - and:
+                  - "#approved-reviews-by>=1"
+                  - "author~=^(dave[-]gantenbein|dejanzele|richscott|nikola[-]jokic|sudiptob2|dcoric|fabiovincenzi|pavlovic[-]ivan)"
+        title:
+          Two are checks required.