chore: migrate to owlbot (#420)

* chore: migrate to owlbot

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

.github/.OwlBot.lock.yaml

@@ -0,0 +1,3 @@
+docker:
+  image: gcr.io/repo-automation-bots/owlbot-java:latest
+  digest: sha256:b328758e5113c392d3eccad613c2b18097eaebcb4d8bf77fab0326a6cad90bc7

.github/.OwlBot.yaml

@@ -0,0 +1,16 @@
+# Copyright 2021 Google LLC
+#
+# 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.
+
+docker:
+  image: "gcr.io/repo-automation-bots/owlbot-java:latest"