update purescript-test-unit to v6

Author: tel

bower.json

@@ -18,7 +18,7 @@
   },
   "devDependencies": {
     "purescript-quickcheck": "^0.12.2",
-    "purescript-test-unit": "^5.0.0"
+    "purescript-test-unit": "^6.0.0"
   },
   "repository": {
     "type": "git",