start to use `cargo upgrade` instead of `cargo update`

[mavilein]

@carmenberndt recently looked into how we could ensure to use the same version of used crates everywhere in our workspace.

The idea is to use cargo-edit in order to update our dependencies. This task is about two things:

1. Document how team members are supposed to use cargo upgrade from now on.
2. Maybe addd some convenient aliases to our Makefile