chore(deps): update duckduckgo-search requirement in /backend

Updates the requirements on [duckduckgo-search](https://github.com/deedy5/duckduckgo_search) to permit the latest version.
- [Release notes](https://github.com/deedy5/duckduckgo_search/releases)
- [Commits](https://github.com/deedy5/duckduckgo_search/compare/v6.1.5...v6.1.7

)

---
updated-dependencies:
- dependency-name: duckduckgo-search
  dependency-type: direct:production
...
Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements.txt

@@ -67,4 +67,4 @@ pytube==15.0.0
 
 extract_msg
 pydub
-duckduckgo-search~=6.1.5
\ No newline at end of file
+duckduckgo-search~=6.1.7
\ No newline at end of file