Switch htmltest to be run in cron

Discussed this with the team. Seems the benefits outweigh the effort.
htmltest does not work in many corner cases and it is confusing people
to no end.

Author: mbaldessari

.github/workflows/htmltest.yml

@@ -1,5 +1,7 @@
 name: HtmlTest Action
-on: [push, pull_request]
+on:
+  schedule:
+    - cron: '23 17 * * *'
 jobs:
   build:
     name: Htmltest