update nano to latest version (#135)

diff --git a/package.json b/package.json
index 3f8286c..9134707 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,7 @@
     "moment": "^2.11.1",
     "lodash": "^3.10.1",
     "request": "2.69.0",
-    "nano": "6.3.0",
+    "nano": "6.4.2",
     "json-stringify-safe": "^5.0.1",
     "http-status-codes": "^1.0.5",
     "request-promise": "^1.0.2",