Test over OTP 27 and rebar3 3.23

[paulo-ferraz-oliveira]

Description

I make explicit tests over the newest version of rebar3 over the newest version of Erlang/OTP. Can't add Elixir to the mix, still, but once we can (1.16, 1.17?) the file is easily updated.

• I have performed a self-review of my changes
• I have read and understood the contributing guidelines

[ericmj]

Elixir 1.17 RC will be released soon which you can test with OTP 27.

[paulo-ferraz-oliveira]

Elixir 1.17 RC will be released soon which you can test with OTP 27.

Cool, this can wait then, since I don't think we're in a hurry. I was just trying to assess how ready the action was 😄 I'll prepare the code for 1.17 rc1, in that case. Thanks.

Edit: I'm having the actions run again based on https://github.com/elixir-lang/elixir/releases/tag/v1.17.0-rc.0.

[paulo-ferraz-oliveira]

@ericmj, I'm merging with minor changes to the README (if CI passes), which we can easily patch if they're wrong.

I thought it appropriate to review that file in the scope of this PR.

I also did two minor fixes to the tests: one was failing, one would fail in a year or so, when support for latest Elixir would drop support for OTP 25.