chore(package): update @types/node to version 10.12.21

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "@microsoft/tsdoc": "0.12.5",
     "@types/core-js": "2.5.0",
     "@types/jasmine": "2.8.4",
-    "@types/node": "10.12.20",
+    "@types/node": "10.12.21",
     "conventional-changelog-cli": "2.0.7",
     "fs": "0.0.2",
     "ink-docstrap": "1.3.2",