Bump cdav-library from `6aff347` to `d77d03e`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `6aff347` to `d77d03e`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/6aff347426ca5fdadbc1590e1bc69ef71e697aba...d77d03e55eeffd7c7b184d18685726bb74aad8e2

)

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