rebase: bump github.com/ceph/go-ceph from 0.20.0 to 0.21.0

Bumps [github.com/ceph/go-ceph](https://github.com/ceph/go-ceph) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/ceph/go-ceph/releases)
- [Changelog](https://github.com/ceph/go-ceph/blob/master/docs/release-process.md)
- [Commits](https://github.com/ceph/go-ceph/compare/v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: github.com/ceph/go-ceph
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

vendor/github.com/ceph/go-ceph/rados/object_iter.go

@@ -42,13 +42,13 @@ func (iter *Iter) Seek(token IterToken) {
 // end of the iterator was reached, or the iterator received an error.
 //
 // Example:
+//
 //	iter := pool.Iter()
 //	defer iter.Close()
 //	for iter.Next() {
 //		fmt.Printf("%v\n", iter.Value())
 //	}
 //	return iter.Err()
-//
 func (iter *Iter) Next() bool {
 	var cEntry *C.char
 	var cNamespace *C.char