This is still very far from usable.

Various bridges and bots are still talking to
`matrix-nginx-proxy` instead of the new `matrix-homeserver-proxy` role.
These services need to be reworked. While reworking them,
various cleanups are being done as well as adding Traefik-labels to
those that need them.

update matrix_bot_chatgpt_version to 3.1.0

It wasn't used at all. It doesn't seem like there's a way to control
the log level, judging by:
- 8f9eea4114/.env.example
- 8f9eea4114/src/env.ts

OpenAI changed the model a month ago and broke the bot.
This bump fixes it and adds the default model.

matrix_bot_chatgpt_context=thread

Add support for OPENAI_PRO for ChatGPT pro subscriptions.

Co-Authored-By: Slavi Pantaleev <slavi@devture.com>