Bump deps

```
* use go 1.17 semantics in go.mod
* pin tonistiigi/fsutil dep to match docker/docker's dep
go get -u ./...
go mod vendor
```

vendor/github.com/opencontainers/image-spec/specs-go/v1/index.go

@@ -21,6 +21,9 @@ import "github.com/opencontainers/image-spec/specs-go"
 type Index struct {
 	specs.Versioned
 
+	// MediaType specificies the type of this document data structure e.g. `application/vnd.oci.image.index.v1+json`
+	MediaType string `json:"mediaType,omitempty"`
+
 	// Manifests references platform specific manifests.
 	Manifests []Descriptor `json:"manifests"`
 

vendor/github.com/opencontainers/image-spec/specs-go/v1/manifest.go

@@ -20,6 +20,9 @@ import "github.com/opencontainers/image-spec/specs-go"
 type Manifest struct {
 	specs.Versioned
 
+	// MediaType specificies the type of this document data structure e.g. `application/vnd.oci.image.manifest.v1+json`
+	MediaType string `json:"mediaType,omitempty"`
+
 	// Config references a configuration object for a container, by digest.
 	// The referenced configuration object is a JSON blob that the runtime uses to set up the container.
 	Config Descriptor `json:"config"`

vendor/github.com/opencontainers/image-spec/specs-go/version.go

@@ -22,7 +22,7 @@ const (
 	// VersionMinor is for functionality in a backwards-compatible manner
 	VersionMinor = 0
 	// VersionPatch is for backwards-compatible bug fixes
-	VersionPatch = 1
+	VersionPatch = 2
 
 	// VersionDev indicates development branch. Releases will be empty string.
 	VersionDev = ""