Update tough-cookie in package.json

See: https://www.versioneye.com/Node.JS/tough-cookie/2.3.2; salesforce/tough-cookie#97; salesforce/tough-cookie#92. (A large cookie could cause a slowdown.)

This is not really necessary since fresh installs or installs using package-lock.json already get the 2.3.3 version, but we might as well.

package.json

@@ -34,7 +34,7 @@
     "request-promise-native": "^1.0.3",
     "sax": "^1.2.1",
     "symbol-tree": "^3.2.1",
-    "tough-cookie": "^2.3.2",
+    "tough-cookie": "^2.3.3",
     "webidl-conversions": "^4.0.0",
     "whatwg-encoding": "^1.0.1",
     "whatwg-url": "^6.1.0",