Update unf_ext from 0.0.7.2 to 0.0.7.4 (#38368)

What does this MR do?

• Update a gem unf_ext from 0.0.7.2 to 0.0.7.4
• Resolve an issue #38368 (closed)

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

• This update of unf_ext contains updating the base Unicode version to 9

Why was this MR needed?

• In order to compile on ARM with GCC6

Screenshots (if relevant)

• None

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #38368 (closed)