Bumped fast-json-stringify v4 (#10)

Signed-off-by: Matteo Collina <hello@matteocollina.com>

Author: mcollina

package.json

@@ -28,7 +28,7 @@
     "tsd": "^0.20.0"
   },
   "dependencies": {
-    "fast-json-stringify": "^3.0.0"
+    "fast-json-stringify": "^4.0.0"
   },
   "tsd": {
     "directory": "test/types"