[BUG] app_offline.htm incorrectly uses http (instead of https) links

[iJungleboy]

Oqtane Info

Version - 5.1.2

Describe the bug

When going into offline mode we usually use the app_offline.htm trick.
But the source code references some css files on oqtane.org (this should be reconsidered anyhow, maybe a https//cdn.oqtane.org/offline/05/something.css would be better for long term stability)...

and this file is linked using http:// - which fails if the original site we're temporarily stopping uses https - it will look wrong and you'll see these messages in the console:

Expected Behavior

If the link in the app_offline.htm used https, everything would be fine.

Steps To Reproduce

1. create a new site on https
2. place the app_offline.bak into the root, naming it app_offline.htm

Anything else?

Simple: just fix the link ;)