Bump fastapi from 0.89.1 to 0.109.1 in /backend

Bumps [fastapi](https://github.com/tiangolo/fastapi) from 0.89.1 to 0.109.1.
- [Release notes](https://github.com/tiangolo/fastapi/releases)
- [Commits](fastapi/fastapi@0.89.1...0.109.1)

---
updated-dependencies:
- dependency-name: fastapi
  dependency-type: direct:production
...

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

backend/requirements.txt

@@ -1,5 +1,5 @@
 alembic==1.8.1
-fastapi==0.89.1
+fastapi==0.109.1
 gunicorn==20.1.0
 itsdangerous==2.1.2
 passlib[bcrypt]==1.7.4