serde tests fail in CI

[arturoc]

Cause Serialize and Deserialize derives are used from serde:: instead of serde_derive::

[KodrAus]

Hmm, it looks like our tests have bit-rotted a bit here. If you run them locally with TRYBUILD=overwrite it should update those expected build failure output files.

[arturoc]

I wasn't sure if I should do that. I'll send a different PR with the fix for the trybuild tests and merge it in these ones

[KodrAus]

I should write something up in the contributing docs for it 🙂 If you leave it to me I'll take care of it. I think we might do something special so the output is only checked in beta builds.

[arturoc]

Yes that's what I was thinking. It's only in beta so not sure that running TRYBBUILD even using a beta version would overwrite the right files

[KodrAus]

Thanks @arturoc. I'll merge this one in and rebase my updates to the test output on top.