Update dependency type-is to v1.6.18

Author: renovate-bot

package.json

@@ -22,7 +22,7 @@
     "lodash": "4.17.4",
     "promisify-any": "2.0.1",
     "statuses": "1.3.1",
-    "type-is": "1.6.15"
+    "type-is": "1.6.18"
   },
   "devDependencies": {
     "jshint": "2.11.0",