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/containers/storage/storage.conf

@@ -67,7 +67,7 @@ additionalimagestores = [
 # squashed down to the default uid in the container.  These images will have no
 # separation between the users in the container. Only supported for the overlay
 # and vfs drivers.
-#ignore_chown_errors = false
+#ignore_chown_errors = "false"
 
 # Path to an helper program to use for mounting the file system instead of mounting it
 # directly.
@@ -132,6 +132,10 @@ mountopt = "nodev"
 # device.
 # mkfsarg = ""
 
+# metadata_size is used to set the `pvcreate --metadatasize` options when
+# creating thin devices. Default is 128k
+# metadata_size = ""
+
 # Size is used to set a maximum size of the container image.
 # size = ""