chore: update to gapic-generator-python-1.4.2 (#271)

* chore: update to gapic-generator-python-1.4.2 (REST transport test fixes)

PiperOrigin-RevId: 474313212

Source-Link: googleapis/googleapis@cec7333

Source-Link: https://github.com/googleapis/googleapis-gen/commit/47afba9d36b84cbbaa85d6e3bc34ef65efe624ee
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiNDdhZmJhOWQzNmI4NGNiYmFhODVkNmUzYmMzNGVmNjVlZmU2MjRlZSJ9

* 🦉 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>

Author: gcf-owl-bot[bot]