Bump cdav-library from `1e4d81b` to `723e236`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `1e4d81b` to `723e236`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/1e4d81b3081e02e47223b3041e14dc2d8717fbe6...723e23686b20fb095a36a56ba69032c08318abfc

)

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