add openssh to docker image

What does this MR do?

I'm trying to scan a project which has dependencies which are private projects. When Go tries to fetch the dependencies it normally uses HTTPS, but that doesn't work if they're private (terminal prompts disabled, can't enter username/password). So you do this little trick with git configuration to get Go to fetch dependencies over ssh: GIT_CONFIG_PARAMETERS=url.ssh://git@github.com/.insteadOf=https://github.com/ unfortunately the docker image doesn't have ssh installed so this doesn't work :)

What are the relevant issue numbers?

N/A

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer