Bump cdav-library from `c087ab5` to `76cab48`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `c087ab5` to `76cab48`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/c087ab5af44d1b09c6a92a1054585a9a67796f9e...76cab484266825b67ea0491da5200f1fe391a9a4

)

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