Bump github.com/containers/buildah from 1.11.6 to 1.12.0

Bumps [github.com/containers/buildah](https://github.com/containers/buildah) from 1.11.6 to 1.12.0.
- [Release notes](https://github.com/containers/buildah/releases)
- [Changelog](https://github.com/containers/buildah/blob/master/CHANGELOG.md)
- [Commits](https://github.com/containers/buildah/compare/v1.11.6...v1.12.0)

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

vendor/github.com/containers/common/pkg/unshare/unshare.go

@@ -0,0 +1,22 @@
+package unshare
+
+import (
+	"fmt"
+	"os"
+	"os/user"
+
+	"github.com/pkg/errors"
+)
+
+// HomeDir returns the home directory for the current user.
+func HomeDir() (string, error) {
+	home := os.Getenv("HOME")
+	if home == "" {
+		usr, err := user.LookupId(fmt.Sprintf("%d", GetRootlessUID()))
+		if err != nil {
+			return "", errors.Wrapf(err, "unable to resolve HOME directory")
+		}
+		home = usr.HomeDir
+	}
+	return home, nil
+}