Bump cdav-library from `1940b5a` to `9cf2cea`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `1940b5a` to `9cf2cea`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/1940b5ab6f3f46d5fbe09cd12351f8b0fa0efc7e...9cf2cea9119513287f41f586dbea28b5b2c99ab3

)

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