Bump django-formset-js-improved from 0.5.0.3 to 0.5.0.4

Bumps [django-formset-js-improved](https://github.com/pretix/django-formset-js) from 0.5.0.3 to 0.5.0.4.
- [Commits](https://github.com/pretix/django-formset-js/commits)

---
updated-dependencies:
- dependency-name: django-formset-js-improved
  dependency-version: 0.5.0.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]