Feature Request: Configurable scheme part of returned URIs (at least for the API)

[I don't know if this issue needs discussion on the forum.]

Setup: nginx reverse proxy in front of docker container running Mayan. The reverse proxy is enforcing use of https by returning a 301 message when attempting to access port 80

There seems to be a major breaking change in Python 3.9's urllib.

After moving from Python 3.8 to 3.9 accessing the follow-up documents ("?page=2") of an API call is failing because when following the link in the "next" field is returned while still encrypted. I can see a correct reaction to the URL "http://dms/api/cabinets/?page=2" (returning of the 301 page) and going back to my Python 3.8 environment my tools are still working correctly. Adding code replacing all http-links returned by the API with https-links is giving correct results, too. [Serious digging in the documentation will probably tell me where I went wrong, too].

Still: Please add a configuration setting permitting me to enforce returning https URLs in any case because returning http URLs will nevertheless force a second connection increasing traffic.

[Yes, I'm completely in favor of keeping all the SSL stuff outside Mayan because it enables the user to chose the mechanism he wants for this part including several proxy servers or plain stunnel.]