Use gofumpt to format code

gofumpt (mvdan.cc/gofumpt) is a fork of gofmt with stricter rules.

Brought to you by

	git ls-files \*.go | grep -v ^vendor/ | xargs gofumpt -s -w

Looking at the diff, all these changes make sense.

Also, replace gofmt with gofumpt in golangci.yml.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

list.go

@@ -3,6 +3,7 @@
 package main
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io/ioutil"
@@ -12,8 +13,6 @@ import (
 	"text/tabwriter"
 	"time"
 
-	"encoding/json"
-
 	"github.com/opencontainers/runc/libcontainer"
 	"github.com/opencontainers/runc/libcontainer/user"
 	"github.com/opencontainers/runc/libcontainer/utils"