Upgrade purescript-spec dependency to v3.1.0

Author: felixmulder

bower.json

@@ -13,7 +13,7 @@
     "purescript-aff": "^5.0.0",
     "purescript-random": "^4.0.0",
     "purescript-quickcheck": "^5.0.0",
-    "purescript-spec": "^3.0.0"
+    "purescript-spec": "^3.1.0"
   },
   "license": "MIT",
   "repository": {