Suggest `#[derive(PartialEq)]` on E0369

[estebank]

When PartialEq isn't implemented for a type, like this

error[E0369]: binary operation `==` cannot be applied to type `&Group`
  --> src/tests/a.rs:19:5
   |
19 |     assert_eq!(result.unwrap(), &group);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |     |
   |     &Group
   |     &Group
   |
   = note: an implementation of `std::cmp::PartialEq` might be missing for `&Group`
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

We should suggest #[derive(PartialEq)] on the appropriate type if possible.

Taken from https://blog.frankel.ch/start-rust/1/

[ccgauche]

I'm going to try to fix that as my first contribution!

[jackh726]

Fixed in #86943