Update RedCloth to 4.3.2 for CVE-2012-6684

What does this MR do?

To fix XSS (CVE-2012-6684), upgrade RedCloth to 4.3.2.

Are there points in the code the reviewer needs to double check?

No.

Why was this MR needed?

Security vulnerability in RedCloth (CVE-2012-6684) should be fixed to provide GitLab as a secure software.

What are the relevant issue numbers?

Closes #19169 (closed)

cf. !2037 (merged), !2071 (merged)

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• [n/a] Documentation created/updated
• [n/a] API support added
• Tests
  • [n/a] Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together