Upgrade: [dependabot] - bump @aws-sdk/util-dynamodb

Bumps [@aws-sdk/util-dynamodb](https://github.com/aws/aws-sdk-js-v3/tree/HEAD/packages/util-dynamodb) from 3.620.0 to 3.621.0.
- [Release notes](https://github.com/aws/aws-sdk-js-v3/releases)
- [Changelog](https://github.com/aws/aws-sdk-js-v3/blob/main/packages/util-dynamodb/CHANGELOG.md)
- [Commits](https://github.com/aws/aws-sdk-js-v3/commits/v3.621.0/packages/util-dynamodb)

---
updated-dependencies:
- dependency-name: "@aws-sdk/util-dynamodb"
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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