fix: return raw block CIDs instead of V0 CIDs from AllKeysChan

V0 CIDs are always "dag-pb". Using the "raw" codec indicates that these blocks
are just raw data.

blockstore.go

@@ -224,10 +224,7 @@ func (bs *blockstore) AllKeysChan(ctx context.Context) (<-chan cid.Cid, error) {
 				log.Warningf("error parsing key from binary: %s", err)
 				continue
 			}
-			k, err := cid.Cast(bk)
-			if err != nil {
-				log.Warningf("failed to cast cid: %s", err)
-			}
+			k := cid.NewCidV1(cid.Raw, bk)
 			select {
 			case <-ctx.Done():
 				return