build(deps): bump fakeredis from 1.9.1 to 2.0.0 in /backend

Bumps [fakeredis](https://github.com/cunla/fakeredis-py) from 1.9.1 to 2.0.0.
- [Release notes](https://github.com/cunla/fakeredis-py/releases)
- [Commits](cunla/fakeredis-py@v1.9.1...v2.0.0)

---
updated-dependencies:
- dependency-name: fakeredis
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

backend/requirements-dev.txt

@@ -1,4 +1,4 @@
-fakeredis==1.9.1
+fakeredis==2.0.0
 pre-commit==2.20.0
 pytest==7.2.0
 pytest-responses==0.5.1