Bump maatwebsite/excel from 3.1.66 to 3.1.67 in /backend

Bumps [maatwebsite/excel](https://github.com/SpartnerNL/Laravel-Excel) from 3.1.66 to 3.1.67.
- [Release notes](https://github.com/SpartnerNL/Laravel-Excel/releases)
- [Changelog](https://github.com/SpartnerNL/Laravel-Excel/blob/3.1/CHANGELOG.md)
- [Commits](SpartnerNL/Laravel-Excel@3.1.66...3.1.67)

---
updated-dependencies:
- dependency-name: maatwebsite/excel
  dependency-version: 3.1.67
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]