build(deps): Bump google-cloud-storage from 1.25.0 to 1.26.0 in /backend

Bumps [google-cloud-storage](https://github.com/googleapis/python-storage) from 1.25.0 to 1.26.0.
- [Release notes](https://github.com/googleapis/python-storage/releases)
- [Changelog](https://github.com/googleapis/python-storage/blob/master/CHANGELOG.md)
- [Commits](googleapis/python-storage@v1.25.0...v1.26.0)

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

Author: dependabot-preview[bot]

backend/requirements.txt

@@ -5,7 +5,7 @@ fakeredis==1.2.0
 Flask==1.1.1
 Flask-Cors==3.0.8
 flask-talisman==0.7.0
-google-cloud-storage==1.25.0
+google-cloud-storage==1.26.0
 gunicorn==20.0.4
 python-dateutil==2.8.1
 pytoml==0.1.21