fix: type widening to match gapic, and two typing fixes

[feywind]

Fixes #1707

[leahecole]

To fix CI you might have to pin to an earlier version of promisify until you upgrade to node 18 - there was an accidental minor version bump that should have been a major so 4.0.0 is safe

[generated-files-bot]

Warning: This pull request is touching the following templated files:

• README.md - README.md is managed by synthtool. However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/main/.readme-partials.yaml
• samples/README.md - samples/README.md is managed by synthtool. However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/main/.readme-partials.yaml

[feywind]

To fix CI you might have to pin to an earlier version of promisify until you upgrade to node 18 - there was an accidental minor version bump that should have been a major so 4.0.0 is safe

Yeah, I've been using 18 for local testing, which is probably premature. Hopefully we'll get the 18 support sorted soon on this repo, anyhow.