Bump flask-assets from 2.0 to 2.1.0

Bumps [flask-assets](https://github.com/miracle2k/flask-assets) from 2.0 to 2.1.0.
- [Release notes](https://github.com/miracle2k/flask-assets/releases)
- [Changelog](https://github.com/miracle2k/flask-assets/blob/master/CHANGES)
- [Commits](miracle2k/flask-assets@2.0...2.1.0)

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

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

requirements.txt

@@ -28,7 +28,7 @@ flask==3.0.0
     #   flask-limiter
     #   flask-wtf
     #   govuk-frontend-wtf
-flask-assets==2.0
+flask-assets==2.1.0
     # via -r requirements.in
 flask-compress==1.14
     # via -r requirements.in