chore(package): update spdy to version 4.0.2

Closes #654

Author: greenkeeper[bot]

package.json

@@ -77,7 +77,7 @@
     "mock-require": "3.0.1",
     "nyc": "^12.0.1",
     "semver": "^5.4.1",
-    "spdy": "3.4.7",
+    "spdy": "4.0.2",
     "tom-sawyer": "^0.1.6"
   },
   "engines": {