Bump ssri from 5.3.0 to 6.0.2

Bumps [ssri](https://github.com/npm/ssri) from 5.3.0 to 6.0.2.
- [Release notes](https://github.com/npm/ssri/releases)
- [Changelog](https://github.com/npm/ssri/blob/v6.0.2/CHANGELOG.md)
- [Commits](npm/ssri@v5.3.0...v6.0.2)

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

Author: dependabot[bot]