.NET 8

[TheTedder]

I took the liberty of upgrading to .NET 8 since .NET 7 is out of support. I also updated almost all of our dependencies. This is bound to break something so it's a good idea to test this heavily. The default placeholder JWT private key had to be increased in length because it didn't have enough entropy or something.

[zysim]

1. Gotta allow anonymous fetching of Categories. We really don't need to be authorised for that
2. How do you generate openapi.json again? It's been so long

Also I've done some testing of the API. Not like "running tests" testing, but calling the API itself, locally. Able to register a new user, log in/out, and create leaderboards and categories, but only if we're authorised. So far so good.

All tests pass, too.

[zysim]

Will do more testing tomorrow

[TheTedder]

1. Gotta allow anonymous fetching of Categories. We really don't need to be authorised for that

This PR doesn't touch category logic. Also, we're gonna go through and change all that anyway after account-related flows are done.

[zysim]

1. Gotta allow anonymous fetching of Categories. We really don't need to be authorised for that

This PR doesn't touch category logic. Also, we're gonna go through and change all that anyway after account-related flows are done.

Yeah that's fair. I'll add a ticket for that if there isn't one, already.

[zysim]

Yeah the backend works. Only problems are some action behaviours. I'll list them out in a separate ticket.

#214