Update c/image for golang.org/x/exp

> go get github.com/containers/image/v5@main
> go mod tidy && go mod vendor

This updates c/image with a new version of x/exp.
That package has changed API in an incompatible way,
so just bumping x/exp (as in https://github.com/containers/skopeo/pull/2060 )
would break Skopeo builds.

This updates both c/image and x/exp in lockstep (and nothing
needs updating in Skopeo itself for the x/exp breakage).

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

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

@@ -1084,7 +1084,7 @@ func (e *doubleFastEncoderDict) Reset(d *dict, singleBlock bool) {
 			}
 		}
 		e.lastDictID = d.id
-		e.allDirty = true
+		allDirty = true
 	}
 	// Reset table to initial state
 	e.cur = e.maxMatchOff