Bump cdav-library from `3170b21` to `a2a3fdf`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `3170b21` to `a2a3fdf`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/3170b21e9dccf8b95bbc23c29927734099ba3cc0...a2a3fdfa1b9b7779d74991d1d8ba8a7e66668c63

)

---
updated-dependencies:
- dependency-name: cdav-library
  dependency-type: direct:production
...

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