build(deps): bump github.com/opencontainers/image-spec

Bumps [github.com/opencontainers/image-spec](https://github.com/opencontainers/image-spec) from 1.1.0-rc5 to 1.1.0-rc6.
- [Release notes](https://github.com/opencontainers/image-spec/releases)
- [Changelog](https://github.com/opencontainers/image-spec/blob/main/RELEASES.md)
- [Commits](https://github.com/opencontainers/image-spec/compare/v1.1.0-rc5...v1.1.0-rc6)

---
updated-dependencies:
- dependency-name: github.com/opencontainers/image-spec
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

go.mod

@@ -45,7 +45,7 @@ require (
 	github.com/moby/sys/symlink v0.2.0
 	github.com/moby/sys/user v0.1.0
 	github.com/opencontainers/go-digest v1.0.0
-	github.com/opencontainers/image-spec v1.1.0-rc5
+	github.com/opencontainers/image-spec v1.1.0-rc6
 	github.com/opencontainers/runtime-spec v1.1.1-0.20230823135140-4fec88fd00a4
 	github.com/opencontainers/runtime-tools v0.9.1-0.20221107090550-2e043c6bd626
 	github.com/opencontainers/selinux v1.11.0