Bump github.com/containers/storage from 1.20.2 to 1.21.0

Bumps [github.com/containers/storage](https://github.com/containers/storage) from 1.20.2 to 1.21.0.
- [Release notes](https://github.com/containers/storage/releases)
- [Changelog](https://github.com/containers/storage/blob/master/docs/containers-storage-changes.md)
- [Commits](https://github.com/containers/storage/compare/v1.20.2...v1.21.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

vendor/github.com/klauspost/compress/zstd/decoder.go

@@ -85,6 +85,13 @@ func NewReader(r io.Reader, opts ...DOption) (*Decoder, error) {
 	d.current.output = make(chan decodeOutput, d.o.concurrent)
 	d.current.flushed = true
 
+	// Transfer option dicts.
+	d.dicts = make(map[uint32]dict, len(d.o.dicts))
+	for _, dc := range d.o.dicts {
+		d.dicts[dc.id] = dc
+	}
+	d.o.dicts = nil
+
 	// Create decoders
 	d.decoders = make(chan *blockDec, d.o.concurrent)
 	for i := 0; i < d.o.concurrent; i++ {
@@ -399,19 +406,6 @@ func (d *Decoder) Close() {
 	d.current.err = ErrDecoderClosed
 }
 
-// RegisterDict will load a dictionary
-func (d *Decoder) RegisterDict(b []byte) error {
-	dc, err := loadDict(b)
-	if err != nil {
-		return err
-	}
-	if d.dicts == nil {
-		d.dicts = make(map[uint32]dict, 1)
-	}
-	d.dicts[dc.id] = *dc
-	return nil
-}
-
 // IOReadCloser returns the decoder as an io.ReadCloser for convenience.
 // Any changes to the decoder will be reflected, so the returned ReadCloser
 // can be reused along with the decoder.