chore(librarian): onboard to librarian (#2479)

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@sha256:4e3486fee9eba44b75a18c67f0c60fa0c4af675132305e3ff3fae2e9b94f94bb
+libraries:
+  - id: gapic-generator
+    version: 1.29.0
+    apis: []
+    source_roots:
+      - .
+    preserve_regex: []
+    remove_regex: []
+    tag_format: v{version}

.github/.OwlBot.yaml

@@ -1,5 +1,9 @@
 # Changelog
 
+[PyPI History][1]
+
+[1]: https://pypi.org/project/gapic-generator/#history
+
 
 ## [1.29.0](https://github.com/googleapis/gapic-generator-python/compare/v1.28.3...v1.29.0) (2025-10-23)