Simplify CI

[whatyouhide]

WIP.

[whatyouhide]

@josevalim looks like in OTP 26 there's a change with the return value for GenServer.init/1. It doesn't seem to exit anymore? See the CI failure.

I’m out of a it a bit so this might be well known, but it surprised me. Might be this, I think?

Anyway, maybe we just remove the assertion on those or scope it down to OTP <= 25?

[josevalim]

@whatyouhide they changed the meaning of {:error, _} and/or failures inside GenServer.init. I think having a conditional test is indeed better.

[whatyouhide]

@josevalim yeah what's weird is that they say that returning {:error, _} (which is a new possible return value in OTP 26) catches the :EXIT message, but returning {:stop, _} should behave like before. I’m sure I’m misinterpreting the docs, but anyway yeah sounds good!

[whatyouhide]

The failing test is a flaky test that's been around for a while, I will look into it separately.