chore(deps): bump fake-useragent from 2.1.0 to 2.2.0 in /backend

Bumps [fake-useragent](https://github.com/fake-useragent/fake-useragent) from 2.1.0 to 2.2.0.
- [Release notes](https://github.com/fake-useragent/fake-useragent/releases)
- [Commits](https://github.com/fake-useragent/fake-useragent/compare/2.1.0...2.2.0)

---
updated-dependencies:
- dependency-name: fake-useragent
  dependency-version: 2.2.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements.txt

@@ -49,7 +49,7 @@ tiktoken
 langchain==0.3.26
 langchain-community==0.3.26
 
-fake-useragent==2.1.0
+fake-useragent==2.2.0
 chromadb==0.6.3
 posthog==5.4.0
 pymilvus==2.5.0