Bump github.com/containers/storage from 1.14.0 to 1.15.1

Bumps [github.com/containers/storage](https://github.com/containers/storage) from 1.14.0 to 1.15.1.
- [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/v1.14.0...v1.15.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

vendor/golang.org/x/sys/unix/sockcmsg_dragonfly.go

@@ -0,0 +1,16 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package unix
+
+// Round the length of a raw sockaddr up to align it properly.
+func cmsgAlignOf(salen int) int {
+	salign := SizeofPtr
+	if SizeofPtr == 8 && !supportsABI(_dragonflyABIChangeVersion) {
+		// 64-bit Dragonfly before the September 2019 ABI changes still requires
+		// 32-bit aligned access to network subsystem.
+		salign = 4
+	}
+	return (salen + salign - 1) & ^(salign - 1)
+}