chore(deps): bump urllib3 from 1.26.18 to 2.5.0 in /backend

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.18 to 2.5.0.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.26.18...2.5.0)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-version: 2.5.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

backend/requirements.txt

@@ -38,7 +38,7 @@ simplegeneric==0.8.1
 six==1.11.0
 traitlets==4.3.2
 typed-ast==1.1.0
-urllib3==1.26.18
+urllib3==2.5.0
 wcwidth==0.1.7
 Werkzeug==3.0.6