ugrade urfave/cli to v2

cli/server/server.go

@@ -1,7 +1,7 @@
 package server
 
 import (
-	"github.com/urfave/cli"
+	"github.com/urfave/cli/v2"
 )
 
 // ServerCommand defines the `abra server` command and its subcommands
@@ -9,10 +9,10 @@ var ServerCommand = cli.Command{
 	Name:    "server",
 	Aliases: []string{"s"},
 	Usage:   "Manage servers",
-	Subcommands: []cli.Command{
-		serverAddCommand,
-		serverListCommand,
-		serverRemoveCommand,
-		serverPruneCommand,
+	Subcommands: []*cli.Command{
+		&serverAddCommand,
+		&serverListCommand,
+		&serverRemoveCommand,
+		&serverPruneCommand,
 	},
 }