Update minio (#12979)

* update minio docker image to latest stable available on 31/10/2019

* update minio-go dependencies

vendor/modules.txt

@@ -132,7 +132,7 @@ github.com/mattn/go-sqlite3
 github.com/matttproud/golang_protobuf_extensions/pbutil
 # github.com/miekg/dns v1.1.19
 github.com/miekg/dns
-# github.com/minio/minio-go/v6 v6.0.38
+# github.com/minio/minio-go/v6 v6.0.40
 github.com/minio/minio-go/v6
 github.com/minio/minio-go/v6/pkg/credentials
 github.com/minio/minio-go/v6/pkg/encrypt