Update dependencies

Among others, this updates minio-go, so that the new "eu-west-3" zone
for AWS is supported.

vendor/cloud.google.com/go/bigquery/benchmarks/bench.go

@@ -17,16 +17,15 @@
 package main
 
 import (
-	"context"
 	"encoding/json"
 	"flag"
 	"io/ioutil"
 	"log"
 	"time"
 
-	"google.golang.org/api/iterator"
-
 	"cloud.google.com/go/bigquery"
+	"golang.org/x/net/context"
+	"google.golang.org/api/iterator"
 )
 
 func main() {