Update workflow and deps

[JamesDearlove]

Updating workflow dependencies, and also package dependencies as well.

While I was here, I removed the channel cog and dealt with some quick deprecation warnings (ie SQLAlchemy 2)

Closes #105

Update 10th May I've also now gone and:

• Added a Pytest workflow to run Pytest on PRs
• Removed Docker build workflow from PRs
• Rewritten Dockerfile to be multi-stage, which should speed up deployment
• Fixed @andrewj-brown's merge issue

[andrewj-brown]

LGTM conditional on the #94 changes being rebased in.

I assume this'll fix all our deprecation warnings? I can't see anything that touches save-state or set-output, unless they're pulled in via the deps you've updated.

[JamesDearlove]

I assume this'll fix all our deprecation warnings? I can't see anything that touches save-state or set-output, unless they're pulled in via the deps you've updated.

Yeah all those seemingly were part of the outdated deps, which is very convenient

[andrewj-brown]

lgtm still. you've reminded me to do a wider documentation review at some point, cause rn it's all pretty shit

[andrewj-brown]

does that work? poetry just inherently knows which files to do? massive

[JamesDearlove]

Well in this case, its running it on the folder uqcsbot so it's smart enough to know what files to run it on otherwise

[JamesDearlove]

I've also now gone and:

• Added a Pytest workflow to run Pytest on PRs
• Removed Docker build workflow from PRs
• Rewritten Dockerfile to be multi-stage, which should speed up deployment
• Fixed @andrewj-brown's merge issue