Update httparty 0.13.3 -> 0.15.6

What does this MR do?

Update httparty dependency.

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

Why was this MR needed?

Debian already has a newer version of this dependency and syncing the dependencies will help improve the debian package.

Screenshots (if relevant)

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
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

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