Install nullable

Author: JordanMartinez

bower.json

@@ -21,6 +21,7 @@
     "purescript-either": "^6.0.0",
     "purescript-exceptions": "^6.0.0",
     "purescript-node-buffer": "^8.0.0",
+    "purescript-nullable": "^6.0.0",
     "purescript-prelude": "^6.0.0"
   }
 }