Bump serverless from 3.38.0 to 4.1.21

Bumps [serverless](https://github.com/serverless/serverless) from 3.38.0 to 4.1.21.
- [Release notes](https://github.com/serverless/serverless/releases)
- [Changelog](https://github.com/serverless/serverless/blob/main/CHANGELOG.md)
- [Commits](https://github.com/serverless/serverless/commits)

---
updated-dependencies:
- dependency-name: serverless
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>