unittest: Always use "raise" with an argument.

[dpgeorge]

So this code can be compiled with the MicroPython native emitter, which does not support "raise" without any arguments.

[andrewleech]

Oh I wasn't aware of that with the native emitter, I'll keep that in mind for other things in future.

Regardless yes this is a straightforward change that does not change the intent of the functions at all.

It does highlight some slight style inconsistencies in the package already (e, ex) but that doesn't change the function and it's clearer to keep this change minimal.

[dpgeorge]

Thanks for the review!

Oh I wasn't aware of that with the native emitter, I'll keep that in mind for other things in future.

I try to stay away from raise without args, which will be hard to make it work (efficiently) with the native emitter (need to store the current exception somewhere).

I bumped into this issue for micropython/micropython#16216