fix(deps): update dependency http-signature to ~1.4.0

package.json

@@ -34,7 +34,7 @@
     "extend": "~3.0.2",
     "forever-agent": "~0.6.1",
     "form-data": "~2.3.2",
-    "http-signature": "~1.3.6",
+    "http-signature": "~1.4.0",
     "is-typedarray": "~1.0.0",
     "isstream": "~0.1.2",
     "json-stringify-safe": "~5.0.1",