build(deps): bump flask-talisman from 0.7.0 to 0.8.1 in /backend

Bumps [flask-talisman](https://github.com/wntrblm/flask-talisman) from 0.7.0 to 0.8.1.
- [Release notes](https://github.com/wntrblm/flask-talisman/releases)
- [Commits](wntrblm/flask-talisman@v0.7.0...v0.8.1)

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

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

Author: dependabot[bot]

backend/requirements.txt

@@ -4,7 +4,7 @@ datadog==0.42.0
 fakeredis==1.5.0
 Flask==1.1.2
 Flask-Cors==3.0.10
-flask-talisman==0.7.0
+flask-talisman==0.8.1
 google-cloud-storage==1.38.0
 gunicorn==20.1.0
 python-dateutil==2.8.2