Fix goimports error

Co-authored-by: Belinda Liu <bliu@pivotal.io>

command/v7/restage_command.go

 package v7
 
 import (
+	"context"
+
 	"code.cloudfoundry.org/cli/actor/actionerror"
 	"code.cloudfoundry.org/cli/actor/sharedaction"
 	"code.cloudfoundry.org/cli/actor/v7action"
@@ -10,7 +12,6 @@ import (
 	"code.cloudfoundry.org/cli/command/translatableerror"
 	"code.cloudfoundry.org/cli/command/v7/shared"
 	"code.cloudfoundry.org/clock"
-	"context"
 )
 
 //go:generate counterfeiter . RestageActor