Bump league/commonmark from 1.5.8 to 1.6.0
Bump league/commonmark from 1.5.8 to 1.6.0

Bumps [league/commonmark](https://github.com/thephpleague/commonmark) from 1.5.8 to 1.6.0.
- [Release notes](https://github.com/thephpleague/commonmark/releases)
- [Changelog](https://github.com/thephpleague/commonmark/blob/latest/CHANGELOG-1.x.md)
- [Commits](https://github.com/thephpleague/commonmark/compare/1.5.8...1.6.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
JC5/firefly-iii,JC5/firefly-iii,firefly-iii/firefly-iii,firefly-iii/firefly-iii,firefly-iii/firefly-iii,firefly-iii/firefly-iii