fix(tree): amend tree in golang

codes/go/chapter_tree/binary_search_tree.go

@@ -5,8 +5,9 @@
 package chapter_tree
 
 import (
-	. "github.com/krahets/hello-algo/pkg"
 	"sort"
+
+	. "github.com/krahets/hello-algo/pkg"
 )
 
 type BinarySearchTree struct {

codes/go/chapter_tree/binary_tree_bfs.go

@@ -6,6 +6,7 @@ package chapter_tree
 
 import (
 	"container/list"
+
 	. "github.com/krahets/hello-algo/pkg"
 )
 

codes/go/chapter_tree/binary_tree_test.go

@@ -5,8 +5,9 @@
 package chapter_tree
 
 import (
-	. "github.com/krahets/hello-algo/pkg"
 	"testing"
+
+	. "github.com/krahets/hello-algo/pkg"
 )
 
 func TestBinaryTree(t *testing.T) {