Bump cdav-library from `1cefd17` to `4c945b7`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `1cefd17` to `4c945b7`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/1cefd176749fc7a75e47b98b50bd0140393f147a...4c945b7e2f0c40aac7e100260b3c7b43a93147cc

)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>