Turn off the insecure site warning for a dev site?

[monaghanmonaghan is verified member.]

I've seen a setting to disable the UI warning system in Firefox, however, does anyone know how to turn it off for just 1 server?

I have a local development server and therefore the connection is secure by default (as nobody else has access to the LAN). I know I could use a LetsEncrypt, but the server is due to be replaced shortly so something to consider when building the new one