Update go.mod, go.sum and vendor

Running `go mod vendor` generates new additions and deletions.

vendor/github.com/docker/docker/client/container_kill.go

@@ -0,0 +1,17 @@
+package client
+
+import (
+	"net/url"
+
+	"golang.org/x/net/context"
+)
+
+// ContainerKill terminates the container process but does not remove the container from the docker host.
+func (cli *Client) ContainerKill(ctx context.Context, containerID, signal string) error {
+	query := url.Values{}
+	query.Set("signal", signal)
+
+	resp, err := cli.post(ctx, "/containers/"+containerID+"/kill", query, nil, nil)
+	ensureReaderClosed(resp)
+	return err
+}