Upgrade the ZAP weekly Docker image

What does this MR do?

Upgrades the ZAP weekly image used as the base image for DAST to owasp/zap2docker-weekly:w2020-02-10.

What are the relevant issue numbers?

This is a requirement for upgrading DAST to use Python 3 gitlab-org/gitlab#118748 (closed)

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
  • Job definition example
  • Vendored CI Templates (also in CE)
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer