[etcd-backup-restore]

Most notable changes

[DEVELOPER] Revendor etcd library to v3.4.13 and change import paths to go.etcd.io/etcd for etcd and go.etcd.io/bbolt for bbolt. (#269, @shreyas-s-rao)

[OPERATOR] Validator now double checks latest revision by starting an embedded etcd if DB-based revision check fails. This can potentially avoid unnecessary data restoration when etcd terminates abnormally. (#275, @ishan16696)
[OPERATOR] Fix missing alternate full snapshots for some unhibernating shoots. (#272, @shreyas-s-rao)
[OPERATOR] Added support for OpenShift Container Storage (OCS) S3 storage type. (#261, @stoyanr)
[OPERATOR] Fixed the issue with consecutive restoration if backup-restore sidecar doesn't restart in between. (#259, @amshuman-kr)