chore: Update gapic-generator-python to v1.6.1 (#51)

* chore: Update gapic-generator-python to v1.6.1

PiperOrigin-RevId: 488036204

Source-Link: googleapis/googleapis@08f275f

Source-Link: googleapis/googleapis-gen@555c094
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiNTU1YzA5NDVlNjA2NDllMzg3MzlhZTY0YmM0NTcxOWNkZjcyMTc4ZiJ9

* 🦉 Updates from OwlBot post-processor

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>
Co-authored-by: Anthonios Partheniou <partheniou@google.com>

packages/google-cloud-apigee-registry/testing/constraints-3.7.txt

@@ -4,8 +4,6 @@
 # Pin the version to the lower bound.
 # e.g., if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have google-cloud-foo==1.14.0
-# This file is intentionally left empty to test the
-# latest versions of dependencies.
 google-api-core==1.33.2
 proto-plus==1.22.0
 protobuf==3.19.5