chore(librarian): onboard to librarian (#1027)

Towards googleapis/librarian#2459

Author: parthea

.github/.OwlBot.lock.yaml

@@ -0,0 +1,10 @@
+image: us-central1-docker.pkg.dev/cloud-sdk-librarian-prod/images-prod/python-librarian-generator@sha256:97c3041de740f26b132d3c5d43f0097f990e8b0d1f2e6707054840024c20ab0c
+libraries:
+  - id: google-cloud-ndb
+    version: 2.3.4
+    apis: []
+    source_roots:
+      - .
+    preserve_regex: []
+    remove_regex: []
+    tag_format: v{version}