Make date-time test strings properly ISO 8601

test/inputs/schema/date-time.1.json

@@ -1,7 +1,7 @@
 {
   "date": "1985-04-12",
   "time": "23:20:50.52Z",
-  "date-time": "1985-04-12T23:20:50.52Z",
+  "date-time": "2018-08-13T21:31:01+00:00",
   "union-array": ["1985-04-12", "23:20:50.52Z"],
-  "complex-union-array": ["1985-04-12T23:20:50.52Z", "foo", 123]
+  "complex-union-array": ["2018-08-13T21:31:01+00:00", "foo", 123]
 }