Update go.mod and vendor

vendor/github.com/moby/buildkit/exporter/exporter.go

@@ -1,22 +0,0 @@
-package exporter
-
-import (
-	"context"
-
-	"github.com/moby/buildkit/cache"
-)
-
-type Exporter interface {
-	Resolve(context.Context, map[string]string) (ExporterInstance, error)
-}
-
-type ExporterInstance interface {
-	Name() string
-	Export(context.Context, Source) (map[string]string, error)
-}
-
-type Source struct {
-	Ref      cache.ImmutableRef
-	Refs     map[string]cache.ImmutableRef
-	Metadata map[string][]byte
-}