Update buildkit

- updated buildkit to current code in master via:

  go mod edit -require github.com/moby/buildkit@master && go mod tidy && ./hack/update-vendor

Signed-off-by: Alex Couture-Beil <alex@earthly.dev>

vendor/github.com/containerd/containerd/remotes/docker/pusher.go

@@ -354,7 +354,7 @@ func (pw *pushWriter) Commit(ctx context.Context, size int64, expected digest.Di
 	switch resp.StatusCode {
 	case http.StatusOK, http.StatusCreated, http.StatusNoContent, http.StatusAccepted:
 	default:
-		return errors.Errorf("unexpected status: %s", resp.Status)
+		return remoteserrors.NewUnexpectedStatusErr(resp.Response)
 	}
 
 	status, err := pw.tracker.GetStatus(pw.ref)

vendor/github.com/containerd/containerd/remotes/docker/registry.go

@@ -56,6 +56,7 @@ const (
 	// Reserved for future capabilities (i.e. search, catalog, remove)
 )
 
+// Has checks whether the capabilities list has the provide capability
 func (c HostCapabilities) Has(t HostCapabilities) bool {
 	return c&t == t
 }