build: add llvm18 support

[chenrui333]

• odin 2024-05 Homebrew/homebrew-core#171372

cc @laytan

[laytan]

This is a weird one? Why would we need to change things here?

We don't want to run on the latest and greatest llvm in our ci because we also support older versions, and generally wait a bit on upgrading CI/releases.

[chenrui333]

This is a weird one? Why would we need to change things here?

to match with the homebrew build?

[chenrui333]

what is the concern here?

[laytan]

This is a weird one? Why would we need to change things here?

to match with the homebrew build?

Alright, but for the reasons I stated in the last comment we don't necessarily want that.

If we were to make the CI use 18, we would probably want a matrix test to do multiple versions.

[chenrui333]

that is fine, let's do matrix build

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note, this is some common practice I am doing to build alliance between upstream and downstream/homebrew

[laytan]

I would be fine with a matrix, I don't have final say here though

[chenrui333]

updated to use the matrix build