Bump cdav-library from `2fdc838` to `84d7146`

Bumps [cdav-library](https://github.com/nextcloud/cdav-library) from `2fdc838` to `84d7146`.
- [Release notes](https://github.com/nextcloud/cdav-library/releases)
- [Commits](https://github.com/nextcloud/cdav-library/compare/2fdc83816f92fa551e8831f08288edff10c33fad...84d71460310056c1d61d07f02f2d4d14da8860fe

)

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