Upgrade to brakeman v5.1.2

What does this MR do?

• Update brakeman to v5.1.2 (!90 (merged))
  • Updated ruby_parser
  • Fix issue where the previous output is still visible
  • Handle cases where enums are not symbols
  • Support newer Haml with ::Haml::AttributeBuilder.build
  • Fix sorting with nil line numbers

What are the relevant issue numbers?

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