build(deps-dev): bump cdk-assets from 2.19.0 to 2.20.0 (#740)

Bumps [cdk-assets](https://github.com/aws/aws-cdk/tree/HEAD/packages/cdk-assets) from 2.19.0 to 2.20.0.
- [Release notes](https://github.com/aws/aws-cdk/releases)
- [Changelog](https://github.com/aws/aws-cdk/blob/master/allowed-breaking-changes.txt)
- [Commits](https://github.com/aws/aws-cdk/commits/HEAD/packages/cdk-assets)

---
updated-dependencies:
- dependency-name: cdk-assets
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]