dependency: (deps): bump anyio from 4.2.0 to 4.3.0 in /backend

Bumps [anyio](https://github.com/agronholm/anyio) from 4.2.0 to 4.3.0.
- [Release notes](https://github.com/agronholm/anyio/releases)
- [Changelog](https://github.com/agronholm/anyio/blob/master/docs/versionhistory.rst)
- [Commits](agronholm/anyio@4.2.0...4.3.0)

---
updated-dependencies:
- dependency-name: anyio
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

backend/requirements.txt

@@ -1,5 +1,5 @@
 annotated-types==0.6.0
-anyio==4.2.0
+anyio==4.3.0
 asgiref==3.7.2
 certifi==2023.11.17
 cffi==1.16.0