deps: update images to v0.18.0

Update the images dependency to v0.18.0
This includes a change in the Fedora IoT remote configuration which is
now installed through an RPM instead of being hard-coded in the image
definitions.

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

@@ -227,10 +227,7 @@ func (e *Encoder) nextBlock(final bool) error {
 			DictID:        e.o.dict.ID(),
 		}
 
-		dst, err := fh.appendTo(tmp[:0])
-		if err != nil {
-			return err
-		}
+		dst := fh.appendTo(tmp[:0])
 		s.headerWritten = true
 		s.wWg.Wait()
 		var n2 int
@@ -483,7 +480,7 @@ func (e *Encoder) EncodeAll(src, dst []byte) []byte {
 				Checksum: false,
 				DictID:   0,
 			}
-			dst, _ = fh.appendTo(dst)
+			dst = fh.appendTo(dst)
 
 			// Write raw block as last one only.
 			var blk blockHeader
@@ -518,10 +515,7 @@ func (e *Encoder) EncodeAll(src, dst []byte) []byte {
 	if len(dst) == 0 && cap(dst) == 0 && len(src) < 1<<20 && !e.o.lowMem {
 		dst = make([]byte, 0, len(src))
 	}
-	dst, err := fh.appendTo(dst)
-	if err != nil {
-		panic(err)
-	}
+	dst = fh.appendTo(dst)
 
 	// If we can do everything in one block, prefer that.
 	if len(src) <= e.o.blockSize {
@@ -581,6 +575,7 @@ func (e *Encoder) EncodeAll(src, dst []byte) []byte {
 	// Add padding with content from crypto/rand.Reader
 	if e.o.pad > 0 {
 		add := calcSkippableFrame(int64(len(dst)), int64(e.o.pad))
+		var err error
 		dst, err = skippableFrame(dst, add, rand.Reader)
 		if err != nil {
 			panic(err)