chore(deps): bump github.com/containerd/containerd from 1.6.6 to 1.6.15

Bumps [github.com/containerd/containerd](https://github.com/containerd/containerd) from 1.6.6 to 1.6.15.
- [Release notes](https://github.com/containerd/containerd/releases)
- [Changelog](https://github.com/containerd/containerd/blob/main/RELEASES.md)
- [Commits](https://github.com/containerd/containerd/compare/v1.6.6...v1.6.15)

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

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

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/Masterminds/squirrel v1.5.3
 	github.com/Masterminds/vcs v1.13.3
 	github.com/asaskevich/govalidator v0.0.0-20200428143746-21a406dcc535
-	github.com/containerd/containerd v1.6.6
+	github.com/containerd/containerd v1.6.15
 	github.com/cyphar/filepath-securejoin v0.2.3
 	github.com/distribution/distribution/v3 v3.0.0-20220526142353-ffbd94cbe269
 	github.com/evanphx/json-patch v5.6.0+incompatible
@@ -103,9 +103,9 @@ require (
 	github.com/liggitt/tabwriter v0.0.0-20181228230101-89fcab3d43de // indirect
 	github.com/mailru/easyjson v0.7.6 // indirect
 	github.com/mattn/go-colorable v0.0.9 // indirect
-	github.com/mattn/go-isatty v0.0.3 // indirect
+	github.com/mattn/go-isatty v0.0.4 // indirect
 	github.com/mattn/go-runewidth v0.0.9 // indirect
-	github.com/matttproud/golang_protobuf_extensions v1.0.2 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
 	github.com/mitchellh/go-wordwrap v1.0.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/moby/locker v1.0.1 // indirect