Bump maatwebsite/excel from 2.1.x-dev to 3.1.x-dev

Bumps [maatwebsite/excel](https://github.com/Maatwebsite/Laravel-Excel) from 2.1.x-dev to 3.1.x-dev.
- [Release notes](https://github.com/Maatwebsite/Laravel-Excel/releases)
- [Commits](https://github.com/Maatwebsite/Laravel-Excel/commits)

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

Author: dependabot-preview[bot]