Update dependencies

vendor/github.com/kr/pty/doc.go

@@ -0,0 +1,16 @@
+// Package pty provides functions for working with Unix terminals.
+package pty
+
+import (
+	"errors"
+	"os"
+)
+
+// ErrUnsupported is returned if a function is not
+// available on the current platform.
+var ErrUnsupported = errors.New("unsupported")
+
+// Opens a pty and its corresponding tty.
+func Open() (pty, tty *os.File, err error) {
+	return open()
+}