Replace deprecated packages

[ccremer]

This project uses the Echo web framework for serving the website. The Echo framework itself is modular and uses some 3rd party dependencies to implement certain functionalities and middleware.
Some dependencies are from the Gorilla framework (https://github.com/gorilla)

Unfortunately, all Gorilla repositories haven been archived on the 9th of December 2022.

We therefore need to consider replacing those, either with forks or with other replacement dependencies.
We use currently:

• https://github.com/gorilla/sessions (to manage sessions in cookie)
• https://github.com/gorilla/securecookie (to encrypt the session cookie in user's browser)

Alternatives that I've found:

• https://github.com/chmike/securecookie for cookies, seems to be an easy replacement, but it's not that popular, no idea whether this is somewhat secure/production ready.
• https://github.com/kataras/go-sessions for sessions, but I don't particularly like its dependency on the valyala/fasthttp framework

We might also consider integrating necessary parts of the source code of Gorilla's session here. I'm not an expert, but since both projects are BSD3-licensed, this should be fine AFAIU

[ccremer]

@glrf @mhutter @bastjan your thoughts?
We could also wait (keep using archived projects) and see if there are any viable forks coming up, or Echo implements something on their own (unlikely though, they're working on Echo v5).

[mhutter]

I'd just leave it for the time being, I don't think there is value in replacing them currently.