Bump aws-sdk-s3 from 1.20.0 to 1.21.0 (#8926)

Bumps [aws-sdk-s3](https://github.com/aws/aws-sdk-ruby) from 1.20.0 to 1.21.0.
- [Release notes](https://github.com/aws/aws-sdk-ruby/releases)
- [Changelog](https://github.com/aws/aws-sdk-ruby/blob/master/gems/aws-sdk-s3/CHANGELOG.md)
- [Commits](https://github.com/aws/aws-sdk-ruby/commits

)

Signed-off-by: dependabot[bot] <support@dependabot.com>