networknt does not respect max warmup time

[awalterschulze]

This means networknt is usually the slowest to run and times out on geojson.
Here is the fix:

    long iterations = (long) Math.ceil(((double) MAX_WARMUP_TIME) / (coldEnd - coldStart));
-    for (int i = 0; i < MAX_WARMUP_TIME; i++) {
+    for (int i = 0; i < iterations; i++) {
      validateAll(schema, lines, want);
    }